Got the same thing when trying new UI. Gray screen with nothing.
Re-Generation etc all seemed to go OK, just basically didn't work. Had a quick look at Orbiter log but didn't see anything immediately obvious.
Tried it on the windows orbiter as well and same result (although it was a black BG rather than gray).
My lounge MD seems to be suffering a lot more under 0.40. It seems to be using more memory for windowing etc and things like MythTV frontend are strugglling. Couple of questions for you: How much memory do you run in your MDs and does it seem to be enough. My lounge MD used to be CPU bound until I gave it a new graphics card but now it seems to be memory bound (it has 256MB at the moment). Do your MDs have swap files? I can understand why they don't (ie: no local disk) but it seems to be suffering and was wondering if there was a way to put a small local disk in as have it use it as swap only.
Seperate problem arose this morning, internet access was down and couldn't access core. went under house and physically rebooted core. Was fine for a while and just before I left for work was down again. Hope this isn't the sign of a big problem on the core
caused by all my Orbiter regen's last night (they seem to get the core working quite hard)
btw. let us know when you get cameras working and what was needed. Mine is not working but havn't even started to look at that.