This sort of complaint is common if there is a hardware issue. Your post is devoid of details, so I'll copy the usual about pests and let you tell more.
CWSHREDDER has moved. I used Google and find it's now at http://www.spywareinfo.com/~merijn/cwschronicles.html
See if you find a pest.
When my computer is on for a while the window that is currently open freezes on me and the mouse cursor disappears. I try closiing the program using control, alt & delete but nothing happens. I have to reboot.