I had the same problem. Best I could come up with was that it has to do with missing files. I am running a rooted deodexed stock ROM which I had debloated when I had the problem. I reflashed the same ROM and didn't debloat anything major (just the minor stuff) and it works fine. I don't know exactly which item it is that disabled it, there are quite a few with DLNA in the name, as well as sharing, WiFi, etc.
For what it's worth, once you check that box, the PS3 pops up with the DLNA server almost instantly, then you can play music, look at photos, watch videos, etc. Works great!
EDIT: I got curious so I played around in Titanium Backup a little bit. If I freeze Nearby Devices 2.0.0, I can no longer check the box and everything is greyed out. Right next to that in the list is Nearby Service 1.4r476 with the same icon. An educated guess would tell me you need both to make it work. Hope that helps.