I think I have this same issue.
Lately, I noticed I get malware, that redirects me to fake websites while I browse. I installed clamtk and clamav, and it worked. But I recently updated eveything: the GUI seems nicer and there are more feature, but it doesn't work.
If I select a folder to be analyzed, an "Virus analyzer" window appears, freezes for few seconds, and then says that no menace was found. But it actually didn't analyze anything. I'm using trusty.
clamscanfrom the command line and add its output to the question? Learn how to use it in the terminal here: http://askubuntu.com/q/250290/367990 – Byte Commander Mar 22 '16 at 15:57