areas "whiting out"

ok first i thought it was my drivers for my nvidia based card so i rolled them back to the 66s and i still have this problem. If I choose the spot plane view from time to time the scenery would "white out" on me and at first i thought i was flying through a cloud. I left it alone and waited to see if this was true but then after a while the colors would come back and its a clear day and i reversed my viewing angle to see if i did really fly through a cloud but there is no clouds. Anyone else have or had this problem and did anyone find a soultion?ps it also happens in any view but it spot plane view i notice it morethanksPaul