I found out this morning that my website had been compromised and was infected with a couple viruses. My hosting company informed me that this could have occurred because my computer was infected. avast had shown me nothing to warn me of any viruses and when I opened the program to scan my computer the scan area was blank. There was nothing to click, no scan button and all the options were blank. I have attached a screenshot to show you what I mean.
If someone could explain to me what has caused this I would appreciate it. Perhaps avast has been compromised by something that's already infecting my computer. I tried using a couple online virus scans (McAfee, BitDefender, HouseCall), but they said my PC was clean, so I don't know.