I assume your find is from File::Find, in that case you shouldn't be checking its return value (find(...) or die $!;), since as far as I can tell it doesn't return a useful value - in a quick test it appears to just return the empty string, which is a "false" value in Perl. Hence, the first call to find works fine until it finishes, you test its return value, and then die. The error message you are outputting, $!, is simply staying set at whatever its last value was, and does not necessarily relate to the call of find.

If you still think File::DosGlob is the problem, you should look at @dir_regex with Data::Dumper (see the Basic debugging checklist).