How to stop my samsung galaxy s2 to stop hanging up after 2 hours

trade it in for a new one before it goes all the way out

try to clean the terminal points.
if not used.
replace it with brand new terminals or good ones.

Have gort your battery status checked?

try recharging the device completely and see if it will power up

t4y645y65yt4t54y54

i have samsung galaxy note 1 GT-N7000. and i have a problem in my cell,when my cell is open and it,s prepared network and prepared SD card and after that it hang.even that the touch system is hanged,pls tell me the salution,thank,s

http://www.hard-reset.com/samsung-galaxy-tab-2-7.0-i705-hard-reset.html

can i do factory reset???

1. try entering null as password.2. try entering your username without @gmail.com3. Combine 1 and 24. Call yourself from another phone, answer, without hanging up press the home button, then menu button, settings, try to disable pattern-lock5. Call yourself from another phone, answer, hang-up, directly after hanging up start pressing your buttons like a madman for <30-60 seconds ending with your home button (might take a while to get the timing right). Go into settings and disable pattern-lock.6. Try the normal recover password routine from GMail.com
7. Perform a factory reset. YOU WILL LOOSE all not-synced DATA (SD card will be left untouched).
1-6 are possible workarounds, these doesn't work for everyone but can be worth a try to avoid factory reset. 6. is what should work but hardly never does. 7 - The factory reset always work
Added reference with some additional info, how to factory reset can be found there.Good luck!