Run MSCONFIG and look at the list of start-up items. Now, Google each of these individually and from the Google report, you can decide whether it is necessary to run this programme on startup or not, if not then untick it. Unfortunately, some startup software bypasses this system and uses a registry entry alone to initiaate its loading and running on startup. Getting rid of these is a little more tricky.
I have had trouble with AVG interfering with Superantispyware in the past so I replaced it with Avast - this stopped the conflict, but I suppose I could just as easily removed Superantispyware and relied on Malwarebytes alone. After all, AVG is supposed to stop spyware as well.
If you want to get into the rescue partition of your hard disc, first make sure that you have at least copied the contents of your documents and settings folders onto a separate folder on your hard drive. (backing them up elswhere is preferable). Then, during boot-up, try repeatedly pushing the function keys - it is often F10 or F12. Your computer instruction manual (if you can remember where you put it) may help, or the manufacturers website might help as well. Once you have got into the partition, re-installing XP is laborious but fairly straightforward. After it has finished updating itself, you then have to re-install all your software -starting with your virus protection.
P.P.