I have the same exact problem with a Sony Bravia KDL-22EX320, fast forward/rewind is almost unusable.
But please don't direct me to the FAQ, cause it's not a network problem.
TV is on a wired dedicated fast ethernet network that has no problem at all, and I'm a professional network engineer.
Moreover the TV is correctly identified:
INFO 2012-12-15 22:49:56.324 [pool-5-thread-1] Renderer Sony Bravia EX found on this address: 192.168.33.66
INFO 2012-12-15 22:49:58.340 [pool-5-thread-1] Address /192.168.33.66 has an estimated network speed of: 85 Mb/s
A Panasonic Smart Viera Plasma TV on the same network has no problem:
INFO 2012-12-15 22:59:00.480 [pool-5-thread-3] Checking IP: 192.168.33.44 for Panasonic
INFO 2012-12-15 22:59:05.121 [pool-5-thread-3] Renderer Panasonic found on this address: 192.168.33.44
Moreover other two media servers I tried on the same PC worked like a charm, with the same files.
To be more precise with mpeg2-ps files recorded from DVB-T, when i fast forward the timer moves on, but when I press play the video starts from the beginning:
INFO 2012-12-16 00:37:57.293 [New I/O server worker #1-2] Checking shared folder: F:\PVR
INFO 2012-12-16 00:37:57.293 [New I/O server worker #1-2] Checking shared folder: D:\Programmi\eMule\Incoming
INFO 2012-12-16 00:38:05.152 [StartPlaying Event] renderer: 192.168.33.66, file: F:\PVR\LA7(121120_225105).mpg
With Xvid avi files instead (direct or remuxed) fast forward seems to work at the beginning, but after some seconds or a few stop and forward sequences, video doesn't resume, or stops, or goes out of sync, or jumps parts.
After that buffer bar on the home page starts to go crazy and from there on renders starts to have huge problem with every renderer, so that I have to restart the server.
The same files work well also directly on the Sony TV from a USB drive pen.
So the only thing that doesn't work is PMS+Sony, and it always happened during past 6 months, with many Sony firmware upgrades and PMS and Java upgrades, with config from scratch.