windows 2k and XP make it impossible to uninstall internet explorer. internet explorer is run by iexplore.exe. your problem is with the windows interface (explorer.exe runs windows explorer, your start bar, system try, and so on)
try booting in safe mode (press F8 right when windows starts to load). if you still can't get the same problem in safe mode, you're in trouble. a reformat or repair instllation of windows will be nessesary.
this could have easily been caused by malicious software (viruses, malware, spyware...). usually, the reasons that windows computers are compromised by this stuff are:
1) the use of internet explorer (use mozilla firefox
www.mozilla.com)
2) the lack of any protective software (use avg free edition free.grisoft.com)
3) user negligence. be careful what you download, what sites you visit, and what programs you agree to install.