That's interesting that it actually core dumps. Can you load the core into a debugger and do a stack backtrace? Perhaps that would give you a clue, or at least something you could post somewhere?

The things that usually cause core dumps in Perl are, I think:

• out of memory issues
• flaky builds of Perl
• signal handling

Signal handlers are buggy in Perl and they cause core dumps, quite often. And Net::Telnet is probably using SIGs to handle the timeouts, so... perhaps there's something to build on, there?

One other thing, related sort of to the second item in the above list: did you recently update/reinstall/rebuild your Perl?