I'm using PMS 1.04 on Vista X64 (not as a service.. It's run from my Startup folder), connected to a PS3 running 2.60 firmware.
After a connection has been established with the PS3 (ie: PS3 Media Server shows up within the XMB), if I close down PMS the 'PS3 Media Server' entry remains on the XMB. If I restart PMS then I get another PS3 Media Server entry displayed. If I rescan for media servers on the PS3, then only a single (ie: the currently running) PMS entry is displayed, as I would expect.
I only found out about this when I'd been streaming from PMS to my PS3, then had to reboot my PC after installing something. My PS3 remained on, and showed two PS3 Media Server entries within the XMB.
It's almost like it's not properly closing down/unregistering the current DLNA connection when the PMS application is shut down.