After installing 4.6 a few times I'm still finding issues with how it calculates vertical path following addition of speed and altitude constraints.

I set up a short flight from EGGP RW27 to EGAC RW 22, FL180, ZFW 70.4 and correctly setup the FMS pre-flight.  FP was WAL L10 IOM NELBO MAGEE.  The last few legs were shown as:

IOM    289/FL170
NELBO 240/FL094
MAGEE 240/3680

I modified MAGEE to 180/3000 as it is the last fix before establishing on the localiser for RW22.

The legs page recalculated as follows:
IOM     289/FL180
NELBO  289/FL180
MAGEE 180/3000
This is clearly not correct and the TD was no longer shown.  This issue is repeatable.

I setup exactly the same flight in 2 other aircraft (B737/767 and B737/800) and did not find an issue. I verified the problem on my Windows 7 FSX installation as well as my WinXP installation.

Additionally I find the Vnav behaviour really inconsistent, in another flight I had a leg speed constraint of 220 set and yet the speed bug was at 250, IAS 250 and VNAV switch illuminated.

I dont recall these problems in 4.4 and while I recognise lots of problems have been fixed in 4.6, I'm left with something I dont trust and pretty unusable for my purposes.  I wonder whether anyone else is finding a similar issue, it may of course be related to something about my setup, but its is not obvious what that might be. I'm at a bit of a loss as to how to proceed.

Thanks Mark,

Yes able to work around it and I probably would use FLTCH when getting down into the approach, so thanks for confirmation that I'm not completely bonkers in seeing problems where none exist.  The 757 is such a lovely model and flies nice within its limitations, its just a pain working out what those limitations are

Regards
Gerard