pmdg 737 ngx makes fsx freeze.

Hi guys, im having a problem when using this aircraft. when i want to change from full screen view to a different one, fsx freezes, or the image starts flashing. it also happens when i use time acceleration. example: accidentally i select 8X and when i return to 4X or normal speed the problem happens. i hate when this happens especially when i am on approach and so close to land, because it keeps me from contiung with my flight. im desperate, please help me. 

thanks in advance,

tatin 98