The error message says the perl512.dll not found. Not that is there and it can not use it.
in reply to Re^2: ActiveState perl512.dll error
in thread ActiveState perl512.dll error
I think you'll find that it's pretty much as choroba has said. If your Data/Dumper is from a perl-5.12 installation, then Dumper.dll won't load unless it finds perl512.dll.
If it can't find perl512.dll then you'll get the error message that you posted in the transcript in your first post, and you'll probably also get a pop-up that tells you that perl512.dll could not be found.
Re-installing Data-Dumper might fix the immediate problem, but if there's one module hanging around from a previous perl installation, then there's probably others.