Sounds like you have something running at start up that is reinstalling these items. A virus or sypware. Try installing the following Anti-Spyware programs, boot into safe mode
and run them. The home of Spybot-S&D! Ad-Aware 2007 Free - Lavasoft
If that doesn't take care of it you may need to find them manualy with a process scanner type of software. I would try this next.
There are plenty of places to help with the results of HijackThis too.