I have been using avast for a while now. As we are having problems regarding the spread of virus via USB, I have resorted to scan my USB every time I use it in a different PC. However when I scan my USB, the loading icon appears and I am unable to get the result from my scan. Please advise.

Install McShield and follow these instructions > https://forum.avast.com/index.php?topic=194892.0

Get McShield from here http://www.mcshield.net/