Desk top goes blank/Pop up blockers

1.When I open internet explorer 2 min. later an error report will pop up asking me to send or dont send. I hit dont send then my desk top goes blank and I have to reboot to get it back. What can i do to fix this.

2. I made the mistake of downloading limewire prior to installing norton. I have since installed it but everytime I get online I am hit with an onslaught of pop ups that are driving me crazy. PLEASE HELP ME STOP THIS MADNESS.

Thanks