OK, thanks guys.
Looks like I'll have to rewrite the file-loading code again. It was single-threaded in 0.5, multi-threaded in 0.6, now back to single-threaded. Apparently Vista doesn't like what the compiler produces.
I hope to have a fix ready in the weekend. Vista users should go back to version 0.5 for now. (You can just overwrite the new lra.exe with the old one.)