Doing a lot of tests with OpenPS2Ld lately, I often shut it down, and I agree it is a real pain to have the SMB working in these conditions.
Common user should not experience this problem a lot.
What possibilities I see:
1. Send a close (previous post), but as you explained, it may not be so easy
2. Process the RST packet on the PS2 side
3. is the PS2Client source available ? so we could look what it does (since vsub think it doesn't have this problem)
Edit1: I think implementing the 2 would be the best. But I don't know if it is possible within OpenPS2Loader
Edit2: Looked at the link. PS2Client is on the PC side, I thought it was a PS2 tool. In this case we are not in the same situation, so I'm not sure it would help us. Because we can't (unless there is a configuration parameter for that) change the behavior of the samba server.