Soz I couldn't help via email, as I don't have a clue about this stuff (I hardly ever defrag lol, maybe once every 2 years at most?)
I think you only need to defrag when you're low on diskspace, the theory being because the disk is almost full, the computer would be jumping here there and everywhere to run a program, whereas if everything is in one location on the disk it should run faster - but if you have plenty of unused space, defragging (I think) wouldn't make much difference to running speed (depends how "fragged" the program is I guess)
Wasn't it "MMC.EXE wants to report an error"?
...and was there an option to uninstall the computeractive program? (instead of just deleting it)
Is the program still listed in Start/ Settings/ Add Remove Programs/ Install Uninstall tab?, if it is, you need to uninstall it... if it won't let you uninstall it, then maybe you could try re-installing it, then uninstalling it (so it's properly removed)
That's all I can guess....
Ma®k?