|"should I now uninstall it, like I've done with Spybot?"|
If you wish, although it could be useful if you run into any problems. I should have said that the quick scan is usually quite good enough and it probably means that Malware is not your issue. It's years since I used SpyBot so I don't know how it has changed but MalwareBytes collects no information. Bogus scanners found on the net can do this sort of thing and are best avoided.
If I'm reading you correctly your issue is continuous activity from the hard drive. This often means that some program (or programs) is keeping it going but probably not Malware. Task manager (Ctrl-Alt-Del keys) should pinpoint what is causing most activity, although there are other programs that give more information.
It could be that some unnecessary programs are starting. If you type msconfig in the search then go to the Startup tab you might find some that you don't need (Google will usually tell you what any are that you don't recognise).
I would suggest you run chkdsk which can fix minor HD issues:
If that doesn't help then Seagate's SeaTools is an example of a program that can fully check your drive out. Get the download for Windows from here:
Always pop back and let us know the outcome - thanks
message edited by Derek