Can you narrow the code down to the smallest bit where it locks up, and then paste it in here? I don't see any STL caveats in the XSUB pods (perlxs or perlxstut), so if you can narrow it down to the smallest bit that hangs, perhaps it is something simple to work around. It's tough to eyeball a general problem like hang without the code, in any language.

    --jb