Perl 5.10.1 introduced a one-line change in Cwd.pm that broke debugging on Windows which may be the same issue you're having, see:
https://rt.cpan.org/Public/Bug/Display.html?id=56225
Comment on Re^3: Eclipse / EPIC / Win32, Debugger Problems / perl5db.pl did not return a true value, Perl 5.10.1