Altimeter anomalies

[hopperp 0]

I keep getting a situation in FSX where the aircraft is descending (Iknow because the houses are getting bigger and the attitude indicator shows it is ) but the altimeter is climbing at a rate beyond the aircraft's capability. I haven't experienced this in real life flying I'm happy to say! Any ideas on (a) why this happens and (b) what can I do about it?

[TXHills 17]

One particular aircraft?  All aircraft? 

[hopperp 0]

Sorry for delay replying. I've tried the FSX "built-in" Cessna 172 & it occurs with that but much less pronounced than with my add-on "Flying Club" Piper Warrior. That is the worst one. I bought that because the Warrior is what I'm learning on in real life and I want to use the FSX for practice at home! I'm using Windows 7. 

[GHarrall 494]

I have never seen anything like that happen in any addon or default aircraft. Not much help...sorry.

 

Are you sure you are looking at the altimeter?

[TXHills 17]

I think screen shots are in order - can you supply some that show what is happening?  (Presumably a sequence with a brief explanation of what your plane is actually doing).