DB_files created with RH5.2 using perl-5.004m7-1 cannot be opened with the perl shipping with RH6.0. One more oddety with perl-500503-2: if you create a DB file (using tie) the 'file' command report that the resulting file is just data - however 'file' correctly reports that a DB file created using perl-5.004m7-1 (under RH6.0) is a Berkeley DB Hash file.
You need to convert your databases using db_dump185. The latest perl-5.00503-6 in Raw Hide uses libdb.so.3 (read: Berkeley db2) while the perl in Red Hat 5.2 used the incompatible Berkeley db1. Make sure you also use db_dump185 from glibc in Raw Hide: the executable shipped with Red Hat 6.0 was linked with the wrong library and is not functional.