PC Anti-virus and Mobile Phone
PC Anti-virus is not really intended for mobile phones...
Many PC anti-virus companies always updating a new virus definitions to detect most common viruses on computers that can cause serious problem to it. The virus defitions maybe is only for computers only that may detect new virus instantly and not for mobile phones. However, mobile phones can be scanned by these PC anti-virus and trying to delete whatever virus it has. But most mobile viruses cannot be seen nor deleted by famous PC anti-virus in the world. Most people don't use mobile anti-virus that really intended to it because they mostly direct to the computer through Mass Storage attempting to scan and delete to have a confident afterwars. But unknowingly, mobile viruses mostly are hidden and resulting to damage a mobile phone slowly.
I've experienced with my Nokia N73 cellular phone. It is not grounded but the battery easily drain within just 30 minutes of use. And my battery was new but still the same happen. I found out that there is a virus inside the files that anti-viruses cannot detect it. What my friend adviced to me is that to format the memory card using a PC and then the Phone memory just by typing *#7370# and accepting the command.
After all I did the phone went to normal and very fast accessing in every part of the software. No need to have a mobile anti-virus. The important is don't accept an unknown files via bluetooth and or infrared connections. And avoid dropping that might cause it to be slow while accessing the phone.