|Real hard to say. A standard xp install may work fine if one or more applications get installed. Problem is that some affect others and MS updates affect them all. |
On top of all that is malware. It can do that. Might as well add in bad ram or hard drive.
I'd at least try a restore point to a time when it worked.
If worse comes to worse. Do a recovery to OEM state. Apply security suite and add in all service packs and updates. Then install programs back to the system. Then make an image of the working system.
Google is evil