A lot of times when you’re working on an infected system, it can be difficult to near impossible to get your anti-malware software to install, let alone run.
This is generally because the malware/virus/whatever on your system tries to block known programs from running that might have a chance to remove it. Here’s a few tips to get around that.
First, boot into safe mode. That keeps some of the nastier parts of the viruses from running.
Then, install the Anti-Malware. It should install under safe mode, but if not, try renaming the installer.
Once it is installed, odds are that it still will not run. Go to the directory that it is installed in, and rename the programs exe to something else. Then try to run it directly.
You should now be able to run a scan and remove the infection. Anti-Malware may not be able to remove everything, so try running something like Spybot just to make sure that everything is cleaned off.