Please Look.

[Rian]

I've dealt with a virus similar to this several times in the past. You can't really kill it with an antivirus program, as it tends to pop back up in a couple of hours. Avast tends to remove many system files when it tries to vault the virus, so it's a big pain in the ass to get a virus like this.

There's not much you can do aside from reformatting and installing a fresh copy of windows.