This is a bug in perl 5.8.0, fixed in 5.8.1.

The bug report is mentioned in fully six seperate tickets. This ticket provides additional detail regarding limitations and issues.

You can either upgrade (preferred, given 5.8.0 is nearly two years old), or apply a patch. This ticket mentions a patch, but it is incorrect. Jarkko Hietaniemi follows up in the ensuing discussion with instructions about obtaining a working one.