Morten: It's related to the mix of wx28 and 64-bit. The actual problem arises from a conversion function in wx28 not functioning properly when built under a 64-bit configuration. It's a known wx problem, you can find a link to the wx tracker somewhere on this thread. If I recall correctly, later wx versions (I think starting from wx29) doesn't exhibit this problem.
Obfuscated: I'm very busy nowadays, I'll test it in a couple of days hopefully.