Can you, or anyone else having this problem, try to reproduce running source with this version? I think that should fix it...
This is why I hate windows 8. After Replicating the bug running from source, I checked the log output and figured it out. Apparently it does not like having the "Windows explorer" open to that directory, and will prevent programs from accessing it completely...though windows had no trouble letting the program create the directory in /temp, and delete /raw, it wouldn't let it copy the files; running from source I got an "access denied" error. For some insane reason it could delete the whole directory, but not copy any files to it. Microsoft D:< .
Since this hadn't been a problem with previous versions of the LNP (having the explorer window open to that directory), I really didn't think it would be a problem this time, so I didn't even think about it.
FYI though, the previous version (R5), is still broken; so looks like there was a bug there, and you did fix that problem.