Difficulty leaving my homegroup in windows 7

Ok. Thats not good. I'm going to try and do some of the options on some of the other forums you've helped with. I hope that this works once i've done it.

Thanks for your help anyway.
If there is anything else I can do without formatting my OS drive, that'd be great. Thank you

I've now done 3 system scans and each time it has come up with the same message, which is that windows resource protection did not find any integrity violations. So i'm guessing there is nothing else I can do.