Runscanner is a useful security tool which can help to detect malware that might have infected your PC.
The program starts by scanning all the startup programs, services and drivers on your system and comparing them against a whitelist of known safe applications. And anything that isn't found will be highlighted in red. This doesn't prove it's malware, but will at least get you looking in the right direction, and if you are suspicious of a particular item then it can be removed in a click or two.
Runscanner will also display all the modules currently loaded on your PC (that's the DLLs, mostly). This time it's up to you to browse the list for dubious files, and that can take a while. If you spot a potential suspect, though, right-clicking it will allow you to search for that file name on Google, check the file at VirusTotal, view its properties, delete the file at the next reboot, and more.
An "All Autostart items" is even more useful, listing all the files launched when Windows starts. We don't mean the usual limited list, either: this includes Windows services, drivers, protocol filters and handlers, IE extensions, Explorer shell extensions, print handlers, context menu handlers and many other system areas. Again, a quick right-click and you can check a file for malware, or search for it at Google, and anything you don't need can easily be disabled or deleted.
And other handy tools on offer here include a listed of installed programs, a Host file editor, and a Process Killer, very useful if a particular file is locked and you can't delete it.