Look here for how to:
Look under METHOD II
BEFORE you change the registry keys data,
download iesetup from microsoft and I strongly recommend you isntall firefox just in case you need a working browser in case your ie reinstall does not work.

Also if you have your XP CD, you could go to START -> RUN
and type in sfc /scannow click OK.
It will take a while.

Also if you have Norton AV installed, uninstall it.
McAffee also should go.

http://f%ee.grisoft.com get AVG antivirus
replace the % with an r so it becomes free.
This forum will not show ''free'' in a URL.