The virtual drive shows a disc with a total size of 192kb (mounted via poweriso). If i actually explore the iso in power iso, i can see all the files (about 6-7gb).
This sounds like a problem to me. What iso is it? And have you tried downloading it again? I don't actually know how to do what you're trying to do in windows, but if you have a linux live disk lying around, it would be pretty easy.
Like I say, I don't know much about windows CLI, but have you tried going straight to L drive and then trying to see, then copy all the files? Example:
L:
dir *
copy * K:Forgive me if my syntax is a little off. Something about this command makes me think you're not selecting all the files: copy *.*
To me that selects all files with a . in them. Directories won't have a . in the name, so they won't be included in that statement.
Let me know how you get on.