It looks as though Lincoln A Baxter was right about the Perl 5.8.0 SIG ALRT situation. I modified my code to time out, and it did--until I realized it only times out correctly if the program hasn't "hung" yet. After setting the timeout to 60 seconds for example, the program hangs before the 60 second limit and the timeout won't occur.

Next I'll test the Sys::SigAction solution to see if it works.