my computer has a virus but virus scanners wont find it

ive been having problems with my internet connection usually betwenn 11pm and 2am.Now everything seems to be working fine then my computer suddently goes offline.ive ran scans with malwarebyes,microsoft security essentials and adaware and none of them seem to pick up any infected files.i havnt been looking at porn or downloading dodgy stuff.

Edit:i know my computer has a virus as i ran a panda scan and it got to about 60% and firefox crashed but at least 1 file has a virus(panda picked it up).its a hkey root file how do a access these???

 

hkey files are registry entries.. a reg cleaner should take em out .. use task manager to kill all suspicious processes and then run a proper antivirus like avg

 

ok ive ran AVG but it didnt find anything.did another pandascan and it found an adaware called memory watcher in hkey_classes_root/vbrad.trayicon.I dont know to find this tryed several searches on my computer.any advice on how to get rid of this would be helpful.Even a link to software that will remove it will be helpful.thanx Paula X and ddp for your quick replies any help is appreciated.if you need more info posts and i will give you the info im running windows 7 64bit edition if that helps and firefox

Edit:did a bit of research on google and ran regedit and deleted hkey_classes_root/brad.trayicon and my computer is running faster already.so its all good now.

 

there you go.. a registry editor can stop things bogging everything down.. especially malware entries which have no trojan to run XD

00003428 adware/memorywatcher Adware No 0 Yes No hkey_classes_root\vbrad.trayicon

theres the baby.. adware

http://www.spyany.com/program/article_adw_rm_Memory_Watcher.html

http://vil.nai.com/vil/content/v_100635.htm

check it carefully.. it may still be around.
note:: it will go into the restore points.. part of it's designed function. A restore unless pretty much back to first install will not get rid of it.

 

try combofix that will find things like nothing else. It's not exactly point and click like an anti-virus so it's good to know what you are doing when using it.

 

alright ive got rid of memory watcher.had a couple of adaware spyware cookies as well which i deleted the otherday but i accidently left them in my recycle bin.got rid of them today (stupid mistake really)and now my computer is clean finally.thanx everyone for the help.

@ Memnock ive never head of combofix so i didnt try it.

edit:had problems with atdmt and doubleclick but i managed to delete them and i had a read through of firefox settings i think i have successfully blocked them from getting on my computer.really hope ive blocked them from getting on my computer.

 

well my computer seems fine now.I use updated antivirus software.it checks for updates automatically and downloads and installs them (sometimes i manually check).I don't plan on re-installing my operating system anytime soon.never actually reformatted a system and i think with my computer still being under warrenty if needed i could probably get the place i brought my computer from to reformat it free of charge.If not my brothers always an option.