On a user's laptop (Windows 7 x64), terrible performance led me to suspect a rootkit after ruling almost everything else out. I checked boot entries with Autoruns and ran a full scan with Malwarebytes, and both came up more or less clean. I downloaded RKR, unzipped, ran as admin, but it would not open. I opened the task manager to check and tried reopening the program. Sometimes the process wouldn't even show. Sometimes it would show for ~10s with a fixed amount of memory listed, and then die. Once, I got to the Sysinternals licence agreement, but it died after that. Tried renaming the EXE, no dice. Tried safe mode, no dice.
One thing I haven't done is check the event logs, which I should probably do. Besides that, what mechanism could potentially cause RKR to fail to start? Or is my system likely compromised, requiring a nuke from orbit?
If you suspect a rootkit, don't waste time trying to find it. Wipe and reinstall the system.
Rootkit Revealer does not support and does not run on 64-bit Operating Systems. The fact that Rootkit Revealer fails to run on a windows 7 x64 system tells you nothing.
It was never written to support 64 bit and is no longer being developed. Last version was published in 2006-ish? I believe. Notes on the download page state: