My first install is in C:\Bethesda Softworks\Fallout 3, the Program Files one is just there just in case. Editing the first post for clarity. @Branimirzg: I'll try that. Edit: I found the problem... my FO3 install was installed on Vista, then copy-pasted from my Vista drive to my Win7 drive. This normally works without any problems, but Fallout 3's updater appears to use the extremely shaky method of "check Programs and Features (Win7 version of Add/Remove Programs) for Fallout 3 and find the install directory from there", which requires that I reinstall Fallout every time I upgrade my machine. Which should be sometime this weekend. And this time it'll be a full reinstall of Win7. Lovely.