Two new Free malware scanners have recently been released, one from Comodo and the other from Microsoft:

Comodo's offering is called Comodo Cloud Scanner and interestingly includes a malware scanner [i:2713jdlc]plus[/i:2713jdlc] a junk files/registry cleaning component; I believe that is a first.[quote:2713jdlc]Comodo Cloud Scanner is the lightning fast online service that detects viruses, junk files, registry errors and hidden processes that may be lurking on your computer.[/quote:2713jdlc]
Even though Comodo describe it is an "online service" there is a download required which weighs in at 17.71MB, I find that a tad incongruous. Apparently the 'online' bit is pertaining more to the way in which the scan engine is powered:
[quote:2713jdlc]instead of using your computers processing power to run a scan, CCS connects to Comodo's powerful online servers and gets them to do all the hard work instead.[/quote:2713jdlc]
Read more about Comodo Cloud Scanner and download [url=http://www.comodo.com/home/internet-security/cloud-scanner.php:2713jdlc]HERE[/url:2713jdlc].

Microsoft have also just released their version of a malware scanner/remover called Microsoft Safety Scanner. As with other tools in the genre, there is zero real time protection included and the product is aimed primarily at cleaning pre-existing malware from already infected systems as well as providing an additional on-demand scanning facility:[quote:2713jdlc]The Microsoft Safety Scanner is a free downloadable security tool that provides on-demand scanning and helps remove viruses, spyware, and other malicious software. It works with your existing antivirus software.[/quote:2713jdlc]
The good -> it is portable. The bad -> the download is a hefty 69.5MB. Some 'experts' are also decrying the fact that the MS scanner expires every 10 days, requiring a fresh download. But [large download aside] I don't see that as being a major issue; all software of this type requires an up-to-date definition database in order to retain optimum efficacy, so frequent updates are the norm and often involve fairly sizable downloads.

Microsoft Safety Scanner is available for download [url=http://www.microsoft.com/security/scanner/en-us/default.aspx:2713jdlc]HERE[/url:2713jdlc].