I'm a big fan of "herdProtect". I have a pretty powerful PC at home that's completely isolated on it's own ISP, for a very specific purpose, and it's completely segregated (network wise) from my other PC's, because the nature of it's activity gets tons of spyware, malware, and viruses on it, I mean tons on a monthly basis. I've used many of the products mentioned above on it, and even other ones, and was in the past using about 20-30 different products on it monthly. Many big name products wouldn't find malware on it, while others would, but practically no product consistently found most of them, and I was spending a huge amount of time running all those different programs on it each month, until "herdProtect".
herdProtect supposedly uses 68 different malware engines, most of the major ones, it's very powerful, to the point of being dangerous (false positives), but has many times found malware on it individual big name products miss by themself. It's probably best used by those who really know what they are doing, and who try numerous other mainstream solutions first, because there is the potential of false positives. Allowing an unsure removal of something can mess you up as bad as leaving that stuff on there, such as....worse system performance, lock-ups, program errors, programs opening slow, programs not starting, system reboots, no boot, and BSOD's. However, if you know what you're doing, and what to look for, regarding identifying a "false positive", you should be safe. If you really study the settings in herdProtect, and spend time learning the product, it's not that hard to figure out what's likely a false positive. I've had it take that PC from totally screwed-up, back to fine, more times than any handful of well-known solutions.
Below are some links along with a couple of basic tutorials, but delve in deep and really learn it, before using it, so you understand how to identify what may be "false positives". I would only recommend it to someone as a last resort, who after using maybe 5-30 other common products, still has a screwed-up computer.
As most tutorials for these kind of products state, absolutely create a "system restore point", and/or registry backup, before using it.
http://www.herdprotect.com/
http://www.herdprotect.com/engines.aspx
http://www.sevenforums.com/tutorials...detection.html
http://www.itpair.com/herdprotect-anti-malware-scanner/
Something else you can do if you don't want to mess with "herdProtect", or your PC is so hosed a mainstream program or two isn't helping, go to a site like
www.bleepingcomputer.com or something similar, where the community freely assists in malware removal. Become a member, post in their forum that you need help, an established or senior member will usually come along to assist you, and tell you how to run software and post log files of the results. After you post your log files and they study them, they'll often tell you what needs to be done.