TMR0 stops working

[shahidali55]

Thanks for that Darrel . . .
I've added a .1uf from MCLR to ground, 1k from buttons to VCC. Datasheet states minimum operating voltage is 2 volts. (http://ww1.microchip.com/downloads/e...doc/35007b.pdf)
Sometime back i have also run the clock from a 12 volt lead acid battery (with 7805).
After 3 days, the clock stopped incrementing time, though the display was being multiplexed and the input buttons responded fine.
16F628A also shows the same behavior.
I tried writing a piece of code that resets all TMR0 registers and variables when the time set button is pressed, but no matter what ,TMR0 doesn't seem to come to life until a powerdown reset is done.