Ditto! I'm using the Open Perl IDE abandonware from sourceforge, and I assume from your mention of the perl5db.pl file, you've got the same. I got mine working (see qualifications below) by editing the use statements in the file:

use strict;
no strict "refs";
use Win32; # add this
use Cwd;
use File::Spec;
use IO::Socket::INET;
use feature ':5.10'; # add this
use Switch; # add this if you want to use given/when
[download]

However, the IDE has some 'issues'. You can set a breakpoint only on a statement in the edit window; there is no way to set conditional breakpoints. And for reasons that are beyond me, when you are working with a GUI done in Tkx, you can no longer look at the contents of variables in the variables window - they all say <internal item>.

I cannot make Perl Express work at all, I just keep getting a warning dialog letting me know that the debugger is running.

I am more or less happy with Open Perl IDE within its limitations, but like you I'd love to find a good, working free IDE - I work for a nonprofit and there is zero chance that they will buy software.

Hope my two cents' worth helps.