Monitor "Out of Range" at native resolution

Hi,

I'm struggling with setting my screen resolution to its native 1440x900 under Windows XP Pro SP2. Every resolution works (blurry) from 800x600 to 1400x1150, but the native one causes an "Out of Range" message to be displayed on and by the screen.

I had no such problem while running Vista with modtool'd official ATI Catalyst drivers nor did I under Mac OS. But I had to switch to XP for game, driver compatibility and snappiness.

Researches on Google yielded refresh rate being to high, but my screen only supports 60 Hz from 1024x768 and up (setting it to 70, 72 or 75 Hz in the "Monitor" tab does not actually take effect since 60 Hz is the rate actually mentioned in the OSD menu), so I don't think the refresh rate is causing the resolution not being supported under XP.

So back to XP, I tried the following drivers without success:

• default generic drivers (no 1440x900 listed as supported resolution),
• graphics drivers from the Leopard Bootcamp CD (2.0, also tried with 1.3 beta),
• latest Radeon Omega drivers,
• latest AMD/ATI BootCamp iMac (early 2006) drivers,
• latest ATI Catalyst drivers with modtool applied for Mobility X1600 support.

As stated above, Vista doesn't yield this weird behavior so I also tried installing Vista Plug and Play monitor drivers (monitor.sys and monitor.inf) for each of the displays listed under the "Monitor" branch of the device manager (3 Default Monitor's, 1 Generic Television, 1 or 2 Plug and Play monitor). Some of the devices were subsequently listed with a warning icon in the device manager, and that didn't do the trick.

My hardware configuration is:

• iMac 17", early 2006 (internal display unplugged, because it's dying) which is equipped with a built-in Radeon X1600 graphics card,
• Asus VW193S, external monitor used as main display,
• the monitor is plugged into the iMac through the Apple mini-DVI to VGA adapter.

Thanks in advance!

(Also posted at DriverHeaven.net)

I just tried this method, without success either . Anyway thanks for the suggestion.