Lara crofts pants,
It does sound like you have some pests in the computer. Does this happen while the computer is connected to the Internet?
Read the Guide in the thread:
Guide for Eliminating Spyware, Adware, and Random Popups
After following the guide, if you still have problems, then download
Hijack This! and post the log file here. Do
NOT make any repairs. (Hijack This! pulls up everything, including programs that are supposed to be in your computer.)
Take Care,
Richard