RAT adventure: VNAV disconnected by external WX program...

Hi All,I had funny adventure last night due to autopilot glitch. I noticed that quite often VNAV mode gets disconnected and Altitude Hold kicks in instead. I think it happens due changes of barometric pressure after it is downloaded by external weather program, such as FS Meteo. It may happen that aircraft suddenly appears above cruise altitude due to change of pressure. Before you may even think about adjusting altimeter setting, FMC thinks it has gone crazy and disconnects VNAV mode.Yesterday I decided to check out new Frankfurt Main scenery by one famous developer. Well, my previous flight ended in Tenerife South, so I wanted to fly from there all the way to Frankfurt...that is about 1960 nautical miles. I started the process quite late, about 10 PM... While I downloaded and installed EDDF scenery, made a flight plan with FSNav and manually loaded it into FMC (I like it that way), it was already 12 PM. So I decided to reach cruise altitude and leave 767 on its own devices for the next 4 hours, while I would be taking a nap! :-) Maybe not a brilliant idea in the real world, but who cares when you are flying on a PC! :-) Zero fuel weight was 261 Lbs, I added 90 Lbs of fuel and FMC was showing 40 Lbs remaining fuel estimate in EDDF. All that perfectly fitted into MTOW and MLW limits, leaving generous amount of fuel at the end... My cruise altitude was FL330, and FMC planned to step-climb to FL370 after first 1000 nm. So I set 37000 feet on my MCP.Take-off from GCTS RW08 was fluent, with V-speeds 142, 147 and 154 at flap 15 setting. I flew SID to KORAL, reaching cruise altitude of 33000 ft before that. 767 was relatively lightly loaded and ascended like a rocket... And then... I left it there, flying peacefully at FL330 towards Frankfurt. I checked "Pause at TOD", turned off the monitor and went for some sleep...When I returned to the cockpit in the morning, I was astounded by magnificient sight! B767 was slowly spiralling towards the earth, with engines off, black screens and no power! Also, RAT was deployed... When I looked through the window, I saw magnificient brand new Frankfurt Main scenery below! If I had returned after 10 more minutes, it would have been a major crash site! Well, of course I have read stories like Gimlie Glider and I could take a shot of a dead stick landing into Frankfurt... However, it looked too risky and I had no training in gliding 767s before! So I simply chose to open Fuel Menu and add some fuel :-)))) I managed to turn-on all systems and engines after that and landed visually on RW07L with no further problem...What aparently happened was that VNAV got disconnected before reaching TOD point. You may think all the story happened because the crew was sleeping and did not reset MCP altitude for descent. But the point is, simulation is supposed to be paused before reaching TOD point, if you check the option "Pause at TOD". Instead, VNAV was changed into Alt Hold, so the aircraft went all the way to Frankfurt at 33000 feet and started circling above the runway... Then it ran out of fuel of course and started spiralling down... until it was luckily recovered by sleepy Captain at 7000 feet... after mid air refuelling, Harry Potter style.Flight analysis revealed that 767 ALSO went in circles somewhere over France... It was a complete mystery to me. After several circles it resumed flight path and reached Frankfurt, only to start circling again...Well, it means that you better do not leave the office of LD767 while you are flying. It sounds pretty realistic, doesn't it? :-)Cheers, Happy New Year!Vilius