If you are running Spy-Bot Teatimer it will prevent you deleting the two registry keys which are causing the problem.
I had exactly the same difficulty myself a couple of weeks ago.
The way round it is to uninstall Spy-Bot.
Then delete the registry keys using either Ad-Aware or the new Microsoft Spyware program (or if you are brave enough edit the registry itself using regedit).
After that you can reinstall Spy-Bot and everything should work OK.
G7SWZ