It would be interesting to know what compiler you are using.
g++ (GCC) 3.4.4 (Gentoo 3.4.4, ssp-3.4.4-1.0, pie-8.7.8)
In order to help we need a smaller piece of code that fails.
I realize that, unfortunately I suspect that's not so easy. Since it's a segfault (that occurs after processing a large number of the nodes in the tree), the precise configuration is important. The particular tree is a result of a non-trivial computation. I will try to narrow things down over the weekend, but to be honest I am not very hopeful.
We have found and corrected on error in the 1.33.1 release candidate that might account for this. You could check that by trying the RC_1_33_0 branch.
Is it downloadable, or do I need to check it out of CVS? I will definitely give it a try. Thanks. Dmitriy