My update on this, in case anybody has similar problems: The Western Digital 'Mybook World' network drive had firmware which had not been auto-updated for a couple of years, and the 'Twonky' media server software included in the firmware was a very early version. After updating the firmware and playing around with settings for this media server via the WD control panel, I was able to eventually find a parameter set that works very well. The only nitpicky drawback now is that the selection menu now has several tree-like layers, so 'Photos' have to be selected, then the network drive, then the folder, then photos again - a few extra operations, but then it works great. Sound to accompany the slideshow needs similar extra selection clicks of the remote, but slideshows then look/sound fabulous. I found variable delays between pictures are eliminated by leaving the tv in standby, rather than fully off, since the off state shuts down WiFi, apparently preventing the Bravia and the network drive from keeping the database fresh.
Now very pleased with my purchase.
JimG
