Just adding some news.
I don't why, but when I stop the PSM, it take a very long time before the PSM desepear from the PS3.
Same thing when I have to restart the PSM Http server (after changing an option for exemple), i took also a very long time to do it (I mean more than 2 or 3 minutes). The PSM interface stay inactive for a while, the icon stay displayed on the PS3 also for a while, then after several minutes, the icon disapear from PS3, and it took another very long time before it shows up again...
Something on my network parameters ?