If running "perl -v" "just goes back to the command prompt (without any error message from 'doze?) you have a problem that I can't grok at the moment.

If cmd.exe didn't find perl it would be expected to spit out a complaint on the order of "perl is not recognized as an internal or external command, operable program or batch file."

But, OTOH, if cmd found perl and perl didn't respond to your request for version information, that would say Perl itself is broken. Yet that seems to be at odds with the "Access denied" message you reported earlier.

So, without a clue, perhaps you'll answer the question above... and report what Win7 tells you when you enter "path" at the command prompt, and what distribution of Perl you've installed repeatedly (and whether you were careful about removing all traces of the previous version on each re-install).

HTH ...but I'm not wildly optomistic :(