Any thoughts as to what might be up?
try this
For a repair of avast. Windows, Add Remove programs, select ‘avast! Anti-Virus,’ click the Change/Remove button from the pop-up window, scroll down to Repair, click next and follow.
if this does not help
Check your computer for Malware with
MBAM http://filehippo.com/download_malwarebytes_anti_malware/
update and run quick scan, click the button “remove selected” to quarantine anything found, and restart
SAS http://filehippo.com/download_superantispyware/
Are cookies really spyware and are they dangerous?
http://www.superantispyware.com/supportfaqdisplay.html?faq=26
come back and tell us if it worked
If anything is found other than cookies you may post the scan logs here