I had the exact same problem as you, PMS said "its ready" but PMS didnt show on my ps3 and there was no traffic. I had my windows firewall disabled and no other firewall installed. In my firewall i had javaw allowed to do what ever it wanted in every type of network, home work and public. (but that shouldn't make any diffrent due to the fact that the firewll is disabled.)
What i did was: I enabled the firewall. I removed the javaw rules so i would get the guesting againt next time i started PMS. I started PMS and the firewall asked me again, like it did the first time, how thw firewall should treat javaw. I allowed it to do what ever it wanted on any type of network, like i did the first time. Anyways, after i did this totaly unlogical thing it worked just fine.
Only a microsoft "restart it and it works" solution to a. microsoft problem.
Hardware: laptop with win7 fat ps3 both wired in an simple switch and both with local ip's, no internet, no router, no nothing fance
I am lost. Having similar issues to those stated above and tried countless solutions.
I am having the same problem with wireshack suggesting no data is getting to my PS3, but if i ping my PS3 it responds. Cidero shows that PS3MS is running but it cannot detect the PS3. For that matter in my travels (countless speradic attempts) WMP could not detect it either. But i recall early on - when i had no use for a MS and i was just trying the PS3, it did once connect. But no luck now.
My PS3 is connected wireless-ly to my router and manages to keep me online for MW2 but will not connect to a media server...
I do occasionally get traffic from the PS3 - Source 192.xxx.x.xx Dest. 22.214.171.124 - Leaving group, followed by a joining group(status) on wireshack.
TBH this is probably my last effort regarding making this work on the wireless network. Maybe one day soon ill run a cable. My last effort and probably (looking at time stamps) a year too late.
I also have this problem... but my network connection has a particular configuration: my PC is connected to the router by ethernet cable, and the PS3 is connected to the router by wireless. I think the problem is caused by that mixed connection (wireless and ethernet cable) because i already tried to use a PC connected by wireless to the router and it recognized the PS3. Don't know if your network is configured this away, but since a haven't found a solution maybe someone could try a fix.
The PMS log window display the same messages as you do. In the end it continuesly send the the message "SENDING ALIVE..." and that's it... Thanks (and sorry for my bad english )