I'm not so sure this is a crossover problem, but it didn't fail on Windows so I'm assuming it is.
I have a rather large mail database. Since I have such a large amount of mail and I use it all the time for reference, I synchronize it to my laptop for offline perusal and do a replication on regular basis. If I start a replication and have to stop it at some point during the replication the local mail database will crash Notes. This is 6.5.1 from January of 2004.
The same procedure can be performed on several machines with identical results. I've got a Fedora Core 2 Test 3 machine, a Red Hat Enterprise Linux 3 machine, and SuSE 9.0 machine. All exhibit the same behavior.
When notes crashes NSD leaves a log. The log says that there are a bunch of DLL's that are missing (File not found). I can post the log if necessary, but didn't know how useful it would be here, although most of the DLL's look like windows DLL's not Lotus ones.