I cannot install any programs on Windows XP.  I tried downloading Adobe Reader and when the PROGRAM finishes downloading and I press 'RUN' - it comes up saying that it has encountered a problem and needs to close.  If I send an error report to Microsoft and click on the More Info button it says that I need to download something from this site http://www.nvidia.com/object/winxp_2k_71.89.html - however when I tried to do that the same thing happens - it tells me that the program has encountered and error and will not run it. I tried to install several more programs and same thing happens.  Can anyone help?XP Home or Pro? Service pack? What virus/spyware protection? WHat happened prior to this? Other problems noted? Any recent softrware or hardware changes?

See below.XP Home
Service Pack 2
Trend Micro PC-Cillin 2006
Nothing happened prior?
There have been several occurrances in Word, Excel and Internet Explorer with MENUS not opening at times.
Some SOFTWARE changes, updated Internet Explorer to latest version, deleted some programs such as Adobe (version 5) and Filemaker Pro but nothing significant.
No hardware changes.And what did you use to check for spyware? If nothing, download, install and update Spybot, then run it in safe mode.

Also try the online SCANNER at www.trendmicro.com

If the machine is not clean, all bets are off.

If it is, how about a system restore to a point before this happened, if it was recently.This happend to me. I think it something to do with many un/installations on the computer??
Anyway reparing Windows should fix it. Remember to have the driver disks ready.