laura369,
I use WinRAR (have for years) with Vista Home Premium 64Bit SP1 with no issues at all. I do have a registered version (as a matter of fact, I am using the latest beta right now) if that might make a difference...(it should not).
I never "invoke the program" but simply click (double click) on the archived file and WinRAR "self-starts" and opens a view that lets me see what is in the archive.
When I do archive files (rare in these days of giant hard drives), I have always placed copies of the files I want to archive in my C:\temp directory and point Win RAR to there.
I know this probably is not of much help, but perhaps if you try just double clicking on the archived (zipped) file, it might "self-start" for you...
My Best,
Michael