A couple of suggestions:
1. As a quick'n'dirty workaround, it sounds like you can probably get away with "force install",
cpan> force install MLDBM
2. Why does "make" think /usr/lib/perl/5.8/Config.pm is out of synch?
Please run "ls -l /usr/lib/perl/5.8/Config.pm" and check the time stamp. Please
run "date" and check your system time/date.
If /usr/lib/perl/5.8/* is truly out-of-date, you might want to consider running "touch" ...
or simply er-installing.
If either /usr/lib/perl/5.8 or your CPAN build directory is on a remote share, maybe
all you need to do is synchronize the two hosts.
3. Here's some good background on using/troubleshooting CPAN:
Your .. PSM