It appears that GCC 3.4 may be a bit more strict about compiling old C code. The btparse library that Bookcase uses internally for Bibtex export is a bit crufty, and compilation is failing. I’m not sure yet if it’s due to a bug in how I included the library or in btparse itself, but I’ll try to track it down and get it fixed. Right now, I’m afraid you’r eout of luck with GCC 3.4 and Bookcase.