Hi Microburst2002,
By the way, I never have this problem in the sim because it cannot simulate problems in the static. only in the pitot.
I think this is because, pitots can clog with ice, nesting wasps, bird strike, or be unreliable with radome damage etc.
The only static ports problem I can think of is if they have been taped over by maintenance / engineering. Your outside check before flight should prevent the last case.
Otherwise if IMC, and no GPS data - I can't see how you would determine if you have levelled off either.