This is an issue discovered during a pre-sales opportunity. Basically, it can be reproduced like this:

1. Use a web tier (calling remote slsb ejb from jsp, e.g.) with 2 ejb tiers (for clustering, say, ejb1, ejb2)
2. access it first to ejb1
3. shutdown ejb1, and access it again will failover to ejb2
4. shutdown ejb2 and bring up ejb1, should produce error traces (I don't have now). Will attach it here later.