builthatch - ccleaner has nothing to do with computer security, it removes junk files, not required.
MBAM - is great, it must be updated before scanning, GR8 2nd opinion scanner complements Avast very nicely.
Combofix is a dangerous tool & should be used only to generate a "log" the uploaded to someone trained to interpret it. I use this only when it's 4th & long & no time left on the clock.
TDS Killer - is only for rootkits, where the file hides itself from the OS. Kaspersky makes this tool & should be done on a known infected machine, caution this also finds or generates FP's (false positives)
If you haven't run into trouble using these tools GREAT, but be very cautious, before deleting.
Which brings us to BROWSERS, do you get the same error msg using different Browsers?
You should run ADW Cleaner as it specifically hunts malware, which attaches to browsers. AVAST, MBAM etc. do not look & identify browser related malware. The only other tool that I know for sure, that targets the same is JRT aka Junkware Removal Tool also available at bleeping.
Should you decide to run it, after the scan click log, notepad will open & you will see a long long list of, items to be removed (nothing good will be removed) only known maleware that hides in browsers, will be gone, when you press "clean"
The reason I suspect this is, many here probably use AVAST & so far your the only one complaining. I also curious if it occurs in all browsers, you may get this using IE, them a spyware may just target one browser.