Same thing just happened here, though my ps3 still sees the psms and plays fine!
Everything had been running fine for a couple of days.. right up to the point when I added AVISynth! AVIsynth and its filter had been xed out after the orig install. So after reading about them in the docs I decided to download and install both AVISynth pieces.. As soon as I restarted the server both went green, however the "No Render" problem popped up..
At this point I went to the ps3 and noticed that it still showed the PSMS, only difference was, despite having only 4 specific folders in the shared box, ps3 now sees all my drives. This is new, coming with the "no renderer" flag!
Note: I'm also in the process of trying Mezzmo and Serviio on the same machine. These both continue to run with out issue, in fact, I think I like them both of them over PSMS. Much easier to set up right out of the box, and so far, by my eyes anyway, play just as well.. All have a little shake during full HD frames panning or dollying (all pixels updating) across a Wifi N connection. Not bad but there's a little chop in all of them..
OH.,, I tried locking in the NIC as suggested, it didn't help...
FYI,, I was using WMP12's streamer that worked fine on PS3 and my Samsung LED SmartTV.. In fact,, the only reason Im slugging through all this is the fact that for what ever reason the .MKV containers have become the norm and despite having the right codecs (latest CCCC pack) AND the fact that mkv's play just fine on wmp,, neither the Samsung nor PS3 plays or even shows the files in the folders. OH,, renaming them to .AVI does nothing..