Nope, never had it. I have been relativity virus free ever since I got rid of a CPU loader virus. Keep my CPU at 100% all the time and no one here could figure it out.
If you have a virus that a Anti virus won't pick up download this:
Scan, save to notepad, copy and paste the list to this website to check what background programs are hazardous and simply remove them with this program by checking the box next to the file and clicking fix.
I did that and found a file named Svchost. The reason my Anti-virus didn't pick it up was because its a well known Windows service. The thing that gave it away was the fact that it was hidden in the temp folder and not the windows folder.
I have had this computer for close to a year and I haven't had to reformat it since.