Have you check you memory to see that is good?
Have you run antivirus and malware tests?
Have you scan you disk for error?
Have you added any new programs or software?
How about hardware everything working well?
I am running Windows Xp Home. In the past say 2 weeks it has acted strangely. Slow to load at startup, slow to bring up internet explorer, some other programs. I did format the drive and reload everything. I have also downloaded the latest updates and per Windows Update, it is all updated. Has anyone experienced this lately? I'm wondering if there was an update from Microsoft that caused this?