Microsoft should pull sp3 i am the owner of a computer store , i handle tech part of it 50 machines upgraded to sp3 from a fresh install of sp2 failed.
 
The machines reset in a loop and in some instances failed to boot period.
 
The machines range from dell p4's to quad core intel systems.
 
6 diff brands of motherboards, customers are bringing machines into the shop because they did windows update installed sp3 and there machine no longer boots into windows.

dont spout rubbish figures like this about, the problems are more likley to be caused by whatever image you are using on those computers, here where i work we recently updated all our computers(over 400) and none of them had a problem, we actually noticed a massive speed increase in our toshiba tablet laptops.

You must work for microsoft  what would i gain from lying , and no its not an image i install right from windows xp home sp2 oem cd or xp pro sp2 oem cd.
 
Also no drivers are installed yet so its not a driver issue and its multiple machines from amd to intel.
 
Just 10 mins ago i upgraded a compaq presario SR1734X to sp3  from a fresh install, not only did it get stuck in an infinite reboot but even a system restore failed to put it back to a working condition.
 
30 systems Dell GX260 p4 xp pro sp2 oem installed  fresh, will not install sp3 the install fails to complete.

I installed SP3 on about a dozen of my machines.  I had one system, A8N32-SLI deluxe that crashed in flames and never recovered.  I had to install Vista 32 and SP1 in order to use the machine at work.  I agree, SP3 hosed the 'languages' on all dozen of my machines.  In addition, SP3 hosed my Anti Virus protection program as well as other software applications including diskeeper on every machine.  Although all bit one machine is still running, who knows what will turned up in time hosed by SP3.  I am using the 'free' online support offerd by MS for the one machine I have crashed to the ground.
 
 http://support.microsoft.com/oas/d [...] rid=522131

Just loaded SP3.  Tried Windows Update and CD Disk  (had previouly downloaded the iso file.  Both bombed out with error " ntdll.dll in use".  Rebooted to safe mode and used cd - worked fine, have not had any problems, yet.

You have free support until next year with SP3.  I got a response out of MS through the link I posted, but the techs have never got back to me with a solution!  Apparently, with my A8N32-SLI Deluxe, I must insert a USB drive in the slot THEN the board will boot up Windows XP with SP3.  Of all the stupid... Otherwise I get a stop error telling me my BIOS is not compliant!  It was always compliant before SP3? LOL!  I have them confused over at MS online support!!!!  It should be free.
 
I have SP3 installed on about ten machines now.  Only my A8N32-SLI refused to cooperate.  I had to install Vista on the machine.  Works great now.

Well I upgrade to sp3 also and had zero problems since the day it came out until 3 days ago after a restart it just freezes after the drive checks (I use the /sos option), safe mode even freezes  I tried to do a cd repair but after booting from cd, it loads the drivers and says 'Windows is starting at the bottom and it freezes there also.  Vista 32b runs fine.

Installed SP3 on 2 SP2 systems...well, 1 system using slipstreamed cd...both worked fine but occasional lockups, and the "no DirectX installed" on both machines, but only for NFS Carbon & Most Wanted

I slipstreamed a CD with SP3,WMP11,IE7,DX10, and paved the road and did a fresh install, things worked great, the computer was definitly faster than before, BUT the IE7 wouldn't folow any links from any of my Emails, no matter who it was from, so I wiped the drive and installed XP Pro SP2, later on I'll try to use the SP3 without the IE7, I also understand that the SP3 is a RC2, as it is now is a time bomb, it's going to quit as soon as they release the final version, am I wrong

 
 
When you say in a loop, does it do something like the system loads up to the point (i think where the logo displays  or if using that /sos option, that blue screen with that displays what version of XP, and then reboots itself doing the same thing in a continous loop repeating the same thing?  
 

Just thinking a bit, if all the hardware is a bit different, it is maybe could be a piece of software that is installed on all 50 machines that's causing it.  It could be a driver for a piece of equipment, or certain type of video card, or printer or anything that's repeated in those machines.   I figure MS wouldn't release something with a 99% failure rate, but they obviously can't test everything.   So one theory might be that when SP3 patches, there is some unforeseen incompatibility with some driver or piece of software that's common there.
 
  Then it could make a change in a way that will cause some software originally on there to crash when it comes across the changes in SP3.  Then on  the next reboot the machine starts to reset etc.  It's just a guess, but I think it's not far out of the question.  I could also be some piece of hardware that's in all those machines.  Even something small like a small plug in device could cause it.   Who knows.  Then you'd have to ask your self what software (or even hardware extras) might be similar in the place where you work etc.   I'm just going on the idea that there is probably a pattern there somewhere.   That said, I have no clue or other ideas.    But I did install SP3 on a DELL for a friend and it had no issues what so ever.  I also find that an image backup is a good safe guard before a big patch. .  .  Good luck.

@badge I installed SP3 and at first it seemed fine then all kinds of whacky crap started happening, it got slower and would stall from time to time, so I uninstalled it and the machine is back to normal.
 
I'm glad I had also run across the information about the ASUS A8N32-SLI M/B issues, because if SP3 had panned out that was going to be the next machine I installed it on, dodged the bullet there!
 
Sorry for what you went through!

Haha!  Do you know what the 'official' fix is for the A8N32-SLI Deluxe is?  Ready for this.  Plug a USB device in when you boot with SP3 installed and you are good to go.  I never got that far along the road of technical expertise with my A8N32-SLI.  I installed VISTA 32 and the machine runs better than it ever did with XP.  
 
I experienced the same thing you discribed with the installation of SP3 on our machines.  We use two languages for email, etc.  That was hosed on all of them.  Some were a quick fix by reapplying the second language from Control Panel, other are still misbehaving.  We used a free virus/spyware from Computer Associates on most of our office computers.  That was hosed and had to be uninstalled on all the units.  Imagine what fun I have been having installing all new virus/spyware on the machines.  I guess I am lucky I haven't had even more problems with it.  I hear my wife yelling for me a lot in recent days since SP3's official release!
 
A8N32-SLI Deluxe =crashed to the ground, never recovered installed VISTA 32
A8N-SLI Premium = a few problems
ABIT socket 754= a few problems
HP 1.7 P4 Notebook = a few problems
ASUS 775 945 = a few poblems
ASUS 754 NF3 = a few problems
Intel 775 ATI integrated= only problem was anti virus was hosed
Asus P5B Deluxe= AV hosed
MSI socket 754 = No problem
Mach One939= No problem
EPOX SNF4-SLI 754= No problem, AV hosed
 
 
From M$ support regarding the A8N32-SLI Deluxe:
 
Thank you very much for writing back.  
 
 I understand that we did not test the suggestions on different website but just keep using Windows Vista since it works just fine.
 
 Though we were not able to help you resolve the issue at Microsoft Online Support Services, I hope you are still pleased with our services. If there is anything we could have done better, please feel free to let me know.  
 
 For your convenience, if there is anything unclear when using Windows Vista, please just feel free to contact our Vista support team. Recently Windows Vista SP1 issue is also for free.
 
I have not tried installing SP3 on our 'main' computer in our main office at the front desk.  It's the only XP system we use that I was too chicken to do it.  I don't want to spend three days getting it back to normal and listening to my wife saying, "it worked fine before." Hopefully the hundred or so patches M$ releases to 'fix' SP3 like they did with SP2 will bring this OS back to normal.