Default [Q] Star mobile clone x920

Dear Friend
I bougt a mobile model star x920 with 4 giga ram ,dual sim , i rooted the phone, it was working fine for about 3 months , then it start doing the following :
as long as I"m using it there is no problem, when I"m not using it for a couple of hours it shuts down and not starting untill I remove battery, then it works fine again,,I tried with wifi off,without sim card,I also tried factory data reset,,same problem remains,,,
I flashed the updated rom :
Update Official 20130830_e2001_v89_zlh_hd ( FOR e2001_v89_zlh_hd ONLY )from needrom site,
but the problem still the same ,,do you have any solution ??