I was using an external TV to watch DVDs using the S-Video output of my Thinkpad T41. I checked the box "Extend my windows desktop onto this monitor." That worked, and the icons that don't fit on my desktop then appeared on the TV. The problem is the box above that says "Use this device as the primary monitor" is now unchecked and is greyed out. (That problem occurred immediately.) This is at desktop-right-click / Display Properties / Settings. I have clicked on everything I can find and I can't get that box un-greyed out. I tried rebooting. So, no more watching DVDs until I can check that box again. (When it was working, both my laptop and the TV showed the movie.)
I noticed another thing - I can no longer get to the ATI settings window you see here: http://support.lenovo.com/en_VN/diagnos ... D=HT003603 . That page has the instructions I used to initially enable the external monitor, and I was previously seeing exactly what was there. Now when I right click on the desktop / settings / advanced, I now get a similar window but without all the ATI tabs - it just has General Adapter Monitor Troubleshoot Color Management. It doesn't matter if I had display 1 or 2 selected before hitting advanced. I don't know when the ATI settings tabs got deleted, or if it's related.
Thinkpad T41, Windows XP SP3 Standard video card: ATI Mobility Fire GL 9000 (driver version 220.127.116.1147; 2/6/2007)