after booting up my COMPAQ desktop running Windows XP system, my desktop comes up and my mouse's pointer can be moved anywhere on the screen. the problem is when i press the left mouse button, nothing happens on the screen. it just sits there.
I can get the task manager to come up via the ctl alt del buttons. but it jast sits on the applications tab and i can't get it to do anything. I can't even pull the task manager window around the screen with my mouse. I have rebooted numerous times with no success. Any help would be appreciated. Be specific with your instructions. Thanks! ru1

There are a number of threads like this; sometimes the dektop doesn't populate; sometines several programs don't execute. There are three approaches (in my experience) depending on what's actually the cause:

If you can boot in Safe Mode, do so and try to sniff around system32 folder for any new DLLs or SYS files that have dodgy names and were recently installed. Dodgy names are like qllljhhhhuc.dll. That would indicate an attack and you should run the detection/removal stuff shown in the Virus forum.

You can boot from the XP CD and repair windows as per menu offered.

If you have no XP CD, you might have a factory restore partition on the HDD and your manual will tell you what to do (after you've got your data off in Safe Mode). If Safe Mode doesn't work, then you'll have to attach your disk drive to the USB port of another PC to get your data off.

Hope that all helps.