Invasive Marketing

Each time I go on'line I get infected by 2 "things". I then run Spybot and Ad-Aware to get rid of 'em.
I keep getting these pesky things
Trek Blue Error Nuker
CoolWWWSearch Aff Winshow.

The True Blue pops a window telling me suspicious activity in my PC - do I want to learn about internet security (at least I think it's the True Blue pest).

My question is -
Is there something left in my PC that attracts these pests
OR
am I re-infected each time I go on-line.

It looks like invasive marketing to me. Any tips on killing these pests would be very, very welcome.
If this is the wrong forum for this topic, pls redirect.
/ H