Windows needs qite a few systems to run, however I would suggest you run a good Anti-virus- trogan software package, as you may be sending your files elsewhere.
I find the best (freebies) are :
Adawareclick here by Lavasoft (There are others that sound similar,but are not the same
Spybot click here
a2free by Emisoft
Adaware clears pop up's etc
Spybot clears hidden bot (spyware)
a2free gives a good clean.