in reply to [SOLVED-ISH]DBI Connection Fails with Access Denied on one version of Perl/DBD::MySQL and work on the other

This is a nice tough one. Out of curiosity, does your db password have any special characters in it? If so, you may want to use single quotes when setting it

my $pass = 'PASS_REMOVED';

Also, it's probably not going to shed any light but instead of $! when failing, use $DBI::errstr

Good Luck!