I meant just in general. There's a comment to this effect in diag.t.
And I was thinking of updating the threads module from CPAN -http://search.cpan.org/~jdhedden/threads-1.22/ - assuming you can't update perl itself. I don't know if it will solve anything, but it's the first thing I'd try given the aforementioned comments in diag.t (which you'll find near the beginning of that file).

Cheers,
Rob