It never ceases to amaze me that there are good people in thw world who will spend hours and hours researching, probing and pushing the envelope to discover stuff and are then prepared to spend even more time passing on their knowledge! So a really big thanks, especially to rjeffb and relobes!
I can confirm that the Reg change also works a treat for the combination of VGX-XL302 and Sony KDL-40W2000.
When making the change I noticed that some of the entries were already set to "0", but ensuring that all entries were did the trick.
In case it's useful; things that didn't work were (in order of test):
1) Applying 200MB of Sony updates
2) Applying 200MB of Vista updates
3) Upgrading to Ultimate
4) Applying another 150MB of Vista updates
5) Applying the 7600 GTL latest driver (as recommended by Nvidia video card check s/w)
6) Applying the 7600 GTL HDMI 1.3 Firmware update
7) Re-applying the 7600 GTL latest driver (as recommended by Nvidia video card check s/w)
Indeed steps 5 and 7 created a situation where the the TV and the XL302 just don't seem to be able to get into sync - the TV just flashes the HDMI Connection type (1080i) in the top left hand corner every three or four seconds - recovery was a fun exercise.
When reading through the rest of this topic I did have a panic when all the Ultimate Upgrade issues were raised. Just to check my understanding of the terminiology - the "CableCard" discussion is about an inbound cable connection to the XL3 Cable Tuner from a Cable supplier - and therefore hopefully not relevant to me here in the UK using DVB Tuners and Free to Air transmissions via Antenna (Arial)? My initial panic was that it was about the outbound HDMI connection to the TV! I'll guess I'll let you know after 30 days if I have an issue.
I've just two snags to resolve now:
1) the DVB Tuners sometime losing signal (my problem I think - I shouldn't have 4 take-offs from a single aerial wire!)
2) Loosing sound and picture on wake-up from extended sleep (I'm still absorbing all the previous posts on this subject).
However, on this issue - I have noticed that the XL302 seems to have at least two levels of Sleep. At least, if I force it to "Sleep" the WLAN light stays lit and on "Wake-Up" the HDMI Picture and Sound work. Eventually the WLAN light goes off (not determined how long yet) and on "Wake-Up" they don't - though cycling through an immediate "Sleep"/"Wake-Up" usually bring them back.
I know Vista has at least 4 levels of "Sleep" - the "command line" command POWERCFG /? shows:
S1_supported List devices supporting light sleep.
S2_supported List devices supporting deeper sleep.
S3_supported List devices supporting deepest sleep.
S4_supported List devices supporting hibernation.
Maybe there's something about the level of Sleep that Vista gets to that has a bearing on this issue? Perhaps stopping it getting into a "deep sleep" might help?