WinFixer is a relatively old infection which appeared in 2005 (hence the version. Winfixer 2005). But there's an "updated" release of 2006, and, probably, some other variants.
This type of malware appeared before the devastating Vundo trojan, and is relatively harmless. However, it was created with the ability to exploit IE vulnerabilities and Outlook Express breeches, so it clearly shows the state of PC security on a particular computer.
WinFixer is annoying not only because of its ads and attempts to trick the user into paying for a "full-mode version" of the malware, but also because it installs well over a hundred of files and registry entries. This makes it rather hard to remove Winfixer manually. That's why the use of special tools and/or software is required to erase the malicious code off the hard drive.
HiJackThis is a free utility coded by TrendMicro team. It's insanely popular as a means to show the start-up processes, browser helper objects, cases of code injection, etc. In conjunction with Avenger (another free tool) it makes a powerful weapon to combat Winfixer virus.
Malwarebyte's anti-malware and EMSI a-squared anti-malware are both popular GUI-based programs that effectively detect and remove lots of types of malware, winfixer being one of them.
In my hubpage I provide a more detailed guide on
how to remove winfixer without risking to degrade system performance.
