Please let us know what OS you are using; if it is XP or Me, try using System Restore to a time before you started having problems.
You should not have more then one antivirus program installed on your computer at the same time; someone probably suggested you use Panda's free online scanner (not install Panda on your computer).
Reboot into Safe Mode, go to Add/Remove programs in your Control Panel, and see if you can remove Panda from there.
While in Safe Mode, go to msconfig and enable everything; later you can research (using Google, or asking here), to determine which specific entries, if any, you should disable in msconfig.