I can't blame this on a uncalibrated/malfunctioning proximity sensor. I think you have a defective screen. I suggest taking it to the store where you bought it or a nearby cell phone repair shop. Please let us know how it goes. Good luck!

No I am not on a call when this happens the phone is laying on my desk or table & a call is coming in or the alarm is ringing & I can not answer the call or shut off the alarm.

Does this only happen when you are on a call? Are you using a case? If it does, then it is the proximity sensor turning the screen off to avoid you tapping anything on the screen while on a call. And if you have a case, it may be blocking the proximity sensor.

sometimes when the phone is ideal for awhile & then rings & the screen is blank & I can not answer the call. I must remove the battery & then turn the phone back on. it will be Ok for awhile (a day or two) then go blank (black screen with out icons) again. this happens every few days. the only thing I know to do is remove the battery & reinstall it & turn the phone back on.

Can you please provide more info? Like if your screen goes black it has light on the back, what were you doing when it happens, etc.