is it just that application that wont uninstall or the whole add/remove programs wont open. if thats the case preform a repair on the os. that will fix it. if you decide to repair it let me know what version of windows you have example (xp Home, XP Pro)
the whole add/remove programs wont open. ive found fixes for google, but theres everything but xp fixes. repairing it seems kind of weird since it was just working last week.