USB devices are wrecking Windows ocasionally

Hello everybody. Receive a nice friendly salute in my first post.


---Please give it a read, and try to help me cause this is about to get me nuts---

I have a VAIO notebook model PCG-FR285E (specs here http://support.vaio.sony.co.uk/spe [...] -FR&m=1293). The laptop has Windows XP SP2 installed, and three USB 2.0 ports built in. I use them mostly to connect common USB devices like flash memories, an optical mouse, and lately a HDD.

The problem started few months ago when i was transfering files between a USB memory and the internal HDD and suddenly the laptop hung up (totally freezed). After this, I restarted it and windows came up with this message: "Windows\system32\config\system File Is Missing Or Corrupt". I used a Boot-CD which provided me a tool to read the contents of this folder and of course all the files inside was missed. First I thought it had been a virus, so i decided to just format the disk and reinstalled everything from the scratch. I also cleaned up and scanned the usb memroy with an Antivirus, and nothing was found. It kept working normally some days, but once again while i was doing the same thing, now with a brand new usb mem. the problem happened in the same way.

Since i didn't find anything wrong in windows (i mean everything seemed good: drivers, apps..) This time I began to test every single hardware component of my laptop, run memtest to check RAM, prime95 to test CPU, and other windows independent tools to check other parts. Finally, given that even VAIO support nor in the web was some knowledge about this problem, I decided to purchase a pcmcia card with USB ports..... But as you'd expect, yes!.. It happened again.

Thanks in advance, really appreciated.