Hi Chew,
To get into Safe Mode, as Clive said, you have to reboot your machine, and keep tapping away at the F8 key
while it's starting up. You should eventually get a page of options, one of which should be to start in Safe Mode. We need to know which operating system you are using (XP, Win2K, ME, Win9x, etc), to establish whether you have System Restore, as that will need to be disabled as well.
Just another point, when you installed Ad Aware and Spybot, did you update them before you ran them? That is probably the most important thing, as they will be next to useless without.
Come back to us if you need further help.
Incidentally, if you are going to continue to use Mozilla as your default web browser (recommended), you can uninstall free surfer mk II pop up stopper, as Mozilla has it's own very capable pop up stopper built in.
Another layer of protection can be found in
Spyware Blaster (also free), which blocks spyware before it gets into your computer. Again, you have to keep it updated for maximum efficiency.