I've been running an HP nx7400 laptop with Windows XP SP3 along with a Samsung 2253BW monitor as an extended desktop for about two years now with no problems whatsoever. I downloaded a program this evening to clean out my registry and "make my computer run faster" this evening (didn't work - but it was free, so no worries), and it came with a "Driver Scanner" (Uniblue DriverScanner 2009), which was supposed to scan your drivers to ensure you had the most up-to-date drivers available. I scanned, and it told me I needed to update my monitor driver, so I did.
After I updated the driver, I was suddenly and abruptly unable to use my Samsung monitor as an extended desktop. I can use it as my primary desktop, which I am doing now, and I've managed to enable it as a dual (clone) desktop, but when I select "Extend this desktop" in the graphic properties, nothing happens. I can use either the laptop monitor or the Samsung monitor, not both.
I've tried reinstalling the drivers, uninstalling the drivers, reinstalling them again, unplugging and plugging the monitor, etc. It doesn't appear to be a problem with the monitor, as I'm using it now, but the issue is that it won't allow me to use the extended desktop feature anymore, as it has in the past. I'm guessing it must be a problem with the video card. I googled it, and it appears that by typing "DXDIAG" into the "run" dialogue in the start menu and selecting the "display" tab, I can discover the type of video card I have. Upon doing so, I have a Mobile Intel 945 Express Chipset Family video card (224.0 MB). Let me know if you need more info about the card.
The really odd part about this whole thing is the fact that I've had no problems using the extended desktop feature for the past couple of years, but upon updating the drivers, it absolutely would not work. I've tried rolling back the driver (although not until I'd "updated" with several other drivers) to no avail....tried unplugging the monitor and restarting after uninstalling all of the software+drivers that came with the monitor....tried reinstalling the software+drivers and having the monitor "discovered" by Windows...nothing seems to be working. The laptop definitely "sees" the Samsung monitor. It just won't allow me to use the extended desktop.
Maybe one of you guys can point me in the right direction. I'm pulling my hair out over here!
I have resolved this issue and here's the final report.
I grabbed a separate hard drive and started installing everything from the beginning. Each time I installed something, I changed resolutions and back. Long process, but I nailed it.
It was Spyware Doctor 6.
So as a note to everyone out there, here's a combination that I can replicate with the same effect.
Windows XP Professional SP3 - ASUS P5N73-CM - Spyware Doctor 6
(Latest updates from Microsoft Update, latest nForce drivers, and latest version of Spyware Doctor from Google Updater)
As soon as I installed Spyware Doctor, the resolution was stuck to whatever it was at that time. Didn't matter whether the program was running or not. As soon as I uninstalled Spyware Doctor and restarted windows, everything was back to normal.
When the problem was identified, I swapped the original drive back, uninstalled Spyware Doctor and the problem was fixed.
Thanks everyone for the ideas. Honestly... who could've thought this was in fact the cause.
Anyway, I'm glad it's done