unable to uninstall programs in control panel

For past week or so I have been unable to uninstall ANY program using the 'add/remove' program in Control Panel. When I click on 'uninstall' the 'InstallShield' begins and progresses about 1/2 way, then stops and I get error message "Setup has encountered a problem and needs to close. Sorry for the inconvenience".
I tried 'Restore' but I couldn't restore to any previous point. Have followed MS KB to turn off Restore and then, after rebooting turn it back on, but that removed previous restore points.

Dell Dimension 2200 WinXP with SP2, CPU Intel 1.3MHz, 512Mb, 20GB HD with 11GB free,McAfee 2006 daily updates and no viruses or malware. MS automatic updates and AntiSpyware, AdAware SE with updates 3x a week. Computer seems to run normally otherwise. Do I need to do a 'Repair Reinstall' to get a good copy of 'InstallShield' so I can remove unwanted programs safely?
John Shamblin

 

Someone else had the same problem last week, and this fixed it. If it doesn't it can't hurt. Have your installation CD handy.

start > run > (type) sfc /scannow (there is a space after sfc)
when prompted - put your CD in > reboot