Unhappy [Q] S2 HD LTE Reboots (Shv e-120k)

Friends plssss help me
My s2 hd was running teamleader ROM
suddenly it started restarting
then i flashed it to stock ROM 4.1.2
still it happens
it restarts when the battery percentage goes below 90% and when i open an application
when i put the phone to 'Flight Mode' it works fine and doesnt restart
Whats the solution?????