Recently had problems with computer flashing multiple windows of emails or advertisements.  Thought the was computer infected so I just reformated the HD and reloaded XP Pro and SP2.  After what appeared to be a successful load, I went to load the two programs, which also appeared to load successfully.  When I went to load the new printer drivers, the computer became non responsive.   It appeared to LOCK up.  When I went to see if one of the new programs would boot up, I double CLICKED on the desk top, and mouse pointer/hour-glass would constantly flash at different POINTS on the screen.  So I went to the Start MENU and went to 'all programs'.  When I attempted to leave the 'all programs' to select the program I wanted, it would send me back to the dest top, and I couldn't get either of the programs to start.   I tried a different video card but the problem is the same.  I can't get any of the programs to respond.    Appreciate any advice.Is it a real XP CD that says Microsoft all over it?

A good format and reinstall should solve all problems for a while IF the hardware is functioning CORRECTLY. Did you format the drive during the installation?