On my last flight I have really disgusting problem with VNAV. My speed and path was OK but I got still VNAV Disconnect message. And everytime when I switch VNAV back on it disconnected...What else could be wrong when speed and path is good? What I do wrong? Or is that some kind of bug?

Hello Niko, Hard to tell unless you tell us what exactly the FMS and PFD are telling you. The FMC will display a message in the scratchpad of the CDU. On the PFD you can tell us what modes are current after vnav disconnects, I suppose you will see CWS P here. Anything else you can think of for the flight will be of help, what aircraft, what route, what exactly you were doing and at what point in the flight, details will tell us the problem.Best Wishes,[h4]Randy J. Smith[/h4][h3]P M D G's 747-400[/h3][h4]coming to a runway near you[/h4][/font color]Caution! Not a real pilot, but do play one on TV ;-)AMD 64 3200+ | ASUS KV8 DELUXE | GFORCE 5700 ULTRA @535/1000 | Maxtor 6Y080M0 SATA 80 GIG | 512 DDR 400 | Windows Xp Pro | Windows Xp Pro 64 |