Gnucash start-up error, mcount: tos overflow

Every time I start Gnucash I get an mcount: tos overflow error, Gnucash then starts up properly. After closing a gmon.out file is written, but I can't open it (even with gprof). Anybody else having a similar issue? Advice on where I should start in order to fix this? I've built Gnucash 2.05 on an iBook G4 running 10.4.9 using macports. All ports installed are up to date; slib 3a3 and guile16 are installed. Thanks.