Did you install DBI.pm ?
Did you install DBD::mysql ?
Did you spell it correctly when you use it?

Have a nice day
All decision is left to your taste
Update
Well, that was a quick shot and directly in my foot. Well, well.
But the error you get indicates that Perl cannot find them along with your old nor your new Perl installation, _as I understand_ there is no problem for Unix to have different versions of Perl running at the same time.