Hi,
Running the newest version of the base pack bought today in the sale in FSX.
I consider myself to be well up to speed with the operation of the FMC in Boeings.
The 757 seems to have a mind of it's own when calculating the VNAV profile for descent. My T/D appears and disapears constantly, both on the ND and on the FMC's progress page. Likewise on the legs page the descent estimates next to the waypoints alter from cruise level to estimate and back again in sync with the above T/D issue.  If I add a STAR and select an approach (rather than simply the runway) for my arrival (in this case I'm currently flying to Ibiza (LEIB), it removes the T/D completely, and even shows my fuel prediction for my arrival (in an hours time) as my current fuel load.
Clearly something is up. I have checked and double checked the PERF pages, VNAV pages etc etc and everything is entered correctly (ZFW etc etc). Does anyone have an idea as this will drive me mad and probably result in this first flight in the 757 being my last!
Cheers,
Ian.

I am no expert on VNAV by any means, but it sounds like you're doing everything correctly. setting a STAR or altitude restrictions will allow calculation of the T/D, so everything should be working correctly. The only thing I can recommend is reinstallation.

I get to T/D.  It starts to descend but then it stops at say 20 kft.  Then it actually starts to climb slowly.  then it waits about 50 NM before it descends again and then like a lead balloon.  I've had very few nice landings, if any.  Is there something I'm missing?  Or is there a bug?