I have been using Microsoft Security Essentials (MSE) and a couple of days back my computer got infected by a variety of Ramnit viruses from a usb drive. Although I got MSE to clean it, and then followed up with a thorough scanning with Bitdefender Online Scanner which removed over a 1000 infections, I keep getting alerts from MSE several times a day, and though I keep asking it to clean the same, MSE history shows that Ramnit.I threat was "Allowed". Through Google search I got to know about combo fix and ran it before I saw the preparation guide at the bleeping computer. I am attaching the combo fix log. Please help me, I cannot afford to reformat my computer, I have two hard drives (160GB + 500GB) with a lot of data that has not been backed up. Thanks.