Good morning everyone:Having been an FS9 simmer for many years (and after following the AVSIM forum for quite some time), this is the 1st post of mine regarding a problem that has been driving me crazy for over 2 years (and that did not vanish inspite of several re-installs of FS9, even after a complete harddrive redo):1. Especially when flying on VATSIM one of the standard aircrafts (e.g. B777, Beech 200, LearJet 45, B737 - so obviously not an aircraft related issue), I use FSNav 4.7 which I bought many years ago.2. After takeoff, I might decide to engage the FSNav "fly the flightplan" option, and initially everything works fine.3. Then, at SOME point during cruise, all of a sudden the IAS indicator switches to 000 kts (although I clearly am still cruising with the same speed as before). I recall one VATSIM event from more than one year ago, where I had this issue with a standard B737 (only different livery) where until about 6000 ft the IAS remained at 0, THEN all of a sudden reading again - indicating about 320 kts!!!! You can imagine the controllers going havoc over me rushing in on Oslo Airport like that ... I swear until that moment I had NO idea I was going at about that speed!!!!4. Also (as happened last night on a big VATSIM event), the heading would not work properly anymore, i.e. the right click within the FSNav "fly plane to here" would not react correctly.I remember having read about this issue about 2 years ago, and recall an issue with FSUIPC which would not work together the FreightDogs Scenery (when using which I had same issues as above ... could not find this post in the net anymore, but remember that I had to downgrade my FSUIPC version).I do own a registered FSUIPC version, currently 3.75 installed.Would be great if anyone had a clue, as this is VERY annoying especially when flying online - had to cancel a number of flights already due to this ...Thanks!!!!!Christian

make sure you have the pitot tube heat on. keith

Hi Christian,I agree with Keith, it sounds like you are not using the pitot heater.Also, you have posted a FS9 question in the FSX forum. :(

Have you stepped through the the FMC/CDU to make sure you don't have any DISCONTINUITIES in the Flight plan? These can be removed by presseing the CDU DEL key and applying it to the offending errors. May be a long shot but worth a look.Roger

Thanks, folks, will try. Must say I was 100% sure I had posted into FS9 forums ...CheersChristian