thaw returns a reference to the data structure it creates (just as freeze takes a reference). Only thing I can think of is that the $Pipe->Read() is returning undef. Unfortunately, I haven't used Win32::Pipe and as such am unable to comment on what should be happening. Perhaps a wiser monk would be able to answer.

antirice    
The first rule of Perl club is - use Perl
The ith rule of Perl club is - follow rule i - 1 for i > 1