Sorry to be so direct but do not do it that way - if any one of those strings is coming from the web then you have a giant security hole: What if one of those strings contains something like "; rm -rf /whatever" or "; cat /etc/passwd"? The tainting mechanism is trying to tell you just that, so the point is not to simply blindly untaint stuff, you're supposed to check it for security issues (like removing shell metacharacters) - see perlsec for more on this topic.

The other anon already showed you Capture::Tiny, just to point out another one: capturex from IPC::System::Simple will never invoke the shell, avoiding the above issue of shell metacharacters. It also has the nice feature of more helpful error messages, which sounds like what you need at the moment.

any guesses to what it might be?

I prefer seeing the actual error messages over guessing :-)