Cannot extend my desktop -it recognizes the second monitor, but does nothing

I'm trying to set up a dual monitor display, so that I can extend my desktop to the second monitor, but I can't get the second monitor to enable. The system is detecting it, but it won't enable.

I'm running WinXP with a ATI Radeon x300/x550/x1050 card. The two monitors are connected to the same card (one of them with a DVI/VGA adapter).
When I check the display properties, I see:
1. Default Monitor on ATI RADEON x300/x550/x1050 Series
2. (Default Monitor) on ATI RADEON x300/x550/x1050 Series - Secondary.

When I click the secondary monitor, it asks me if I want to enable. I click yes and it acts like it's enabled. I check the little "Extend my Windows desktop onto this monitor" box, click okay, the system thinks about that for a few secs and then greys out the second monitor again.
The same thing happens when I try it through the Catalyst Control Center - it sees the second monitor, allows me to right-click it and click enable, then it greys-out again. The second monitor is showing just a cloned image of the first monitor.

Anyone has some suggestions? Any help would be much appreciated.

This kind of discussion have been appeared to this forum a number of times and so I would like to suggest you to refer those first and see if that helps you somehow:

http://forums.techarena.in/monitor-v...ds/1298636.htm
http://forums.techarena.in/windows-x...ort/821342.htm
http://forums.techarena.in/monitor-v...ds/1281857.htm
http://forums.techarena.in/monitor-v...ds/1296591.htm
http://forums.techarena.in/vista-help/755956.htm

Thanks for the posts! However, I took a look at them and tried different things, but nothing happened...:no:

THe problem here is that the monitor seems to be expanded (both at Window's and Catalist's Control Panels), but do nothing. It just "blinks". I just see a mirror of the image in the second monitor...