My new Bravia KDL-26EX553 will initially 'see' and play all of my network-shared videos, music files and photos from the 'WD My Book' network drive that I have WiFi networked, but after turning off the tv overnight, (leaving the router and network drive powered), the TV apparently 'forgets' which folder the photos are in, looking for them in the folders in the 'Shared Videos' section of the network hard drive. Seems like the only way I can (temporarily) restore the correct working is to 'factory reset' the TV and re-set it up to the WiFi network from scratch, but that only lasts for a single session. The videos and music files remain all identified and play perfectly, but the TV seems to be looking for jpegs where jpegs ain't stored, and unsurprisingly can't find any! This strikes me as a Bravia software problem, since my PS3 can reliably find all 3 types of media and play them (on a different, non-HD television) without a hitch.
I have also submitted details to Support, but wonder if the forum might be quicker.