I gave it a shot. At first, I got the same error as you, but I played with it for awhile. It finally kicked in. I profiled Math::Pari---

perl -d:DProf /usr/lib/perl5/vendor_perl/5.8.8/i386-linux-thread-multi
+/Math/Pari.pm
dprofpp -g
[download]

I ran it 4 times, and I got different numbers each time. Simon Cozens has said, "Understanding how dprofpp's overhead compensation code works is Not Easy and has meant that I haven't tried to apply overhead compensation in this module. All the data's there if you want to do it yourself. The numbers produced by Devel::DProf are pseudorandom anyway, so this omission shouldn't make any real difference." That says it all. Good luck.