Did you switch from 32bit to 64bit Perl (or vice versa) in the process? I don't believe BerkeleyDB is platform-independent in terms of integer representation, so endian and size matter.
It would help if you gave more information, like the errors you're seeing, what you've done to debug this already, and so on. There's not much to work with here.
Update: Oh, I also recall that changing your underlying BerkeleyDB version will also break things, perhaps Lion moved you forward a version. In either case, you probably have to dump and rebuild your database files for your new configuration.