Looks like I have a virus or trojan that is periodically redirecting some of my Google searches to other random pages. I've done some searching for fixes, and have run virus and malware scans with SecurityCheck, tdsskiller, avast Antirootkit, ComboFix, Malwarebytes, Spyhunter and AVG, and everything has come back clean, but the problem persists.

Any ideas on how to find this thing and kill it?

reset your web browser to factory settings and cleaing cookies and temp files if that does not work try changing you dns settings as some ISP use a redirect dns when its unable to find they site your looking for and computers and routers defualt to auto dns from your ISP.

you can use level3 public dns

4.1.1.1
4.1.1.2
4.1.1.3
4.1.1.4

Thanks, Matrix. I reset settings for IE and Google (I uninstalled Firefox after this started happening). How do I change the DNS settings?

what version of windows do you have

Windows 7 Home Premium

in the lower right hand corner next to the clock click on your local network connection icon and select open network and sharing center. on the left side of sharing center click on change adapter settings,right click on local area connection and select properties,highlit internet protocol version 4 and select the properties button below. and then you will see the setting you can change and i have posted a picture of it. keep in mind if you are using a router you will want to change it in there as well

Great, thanks, I'll set it up. But does the root problem still exist, or do you think it was removed and this is just symptoms of the initial infection?

depends on the cause,if its a hijackeror plug in resetting the browser will correct,if its a dns redirect then changing the dns will help aside from that level3 dns server tend to be faster then most isp any how so page loading might be faster for you. also from the list about you might want to give spybot search and destroy a shot it tend to be one of the better anti spyware programs out in case you have not tried it

http://www.safer-networking.org/en/download/index.html

also a good multi purpose tool for cleaning junk files and registry repair

http://www.iobit.com/advancedsystemcareper.html

Thanks, I'll run Spybot. I forgot to add ASC to my list above - I have that installed and run it regularly.

You may be in for a bit of work. I had this on one of my comps and it was a root virus. I think TDSS root killer finally removed it.

I changed the DNS on my machine, but I don't remember the login/password for the router and some searches are still redirecting. Ran spybot and the Microsoft malware tool (in addition to the stuff listed in the OP), and re-ran TDSS Killer. Everything comes up clean. At this point, I think I'll just wipe it and reinstall the OS. Thanks anyway, guys.