Hijackthis help.. please

Basically my computer get between 15 to 20 viruses daily, My avg detects them when they download which is great but its a real bother i have to scan alot more often to pick up the ones i missed

also when i try to do a malware scan with Ad-Adware SE it picks up a file from systen32, a .dll file and my comp shuts down and blue screens as soon as its detected..

Finally in firefox tabs constantly open which are blank with an extremely messed up homepage (random numbers and letters) and on internet explorer it is plauged with the same page opening and opening..

so if anyone is kind enough to help me out ill be extremely grateful..

well fuck
i know im shit when it comes to complicated problems like this

but at least give a hand everyone starts off somewhere