PIC 16F627a .. Circuit Problem

I programmed a 16F627a chip ..

It worked well on the simulation ,, But I have a problem with the circuit ..

The required output from the microcontroller is maintaned for a bunch of time (sometimes 4 seconds .. sometimes 10 seconds .. ) after the circuit stsrt up ..

That happens although the output is required to remain the same until power is off .. & that what happens on the simulation ..

Any one knows what is wrong ??

Considering you have posted no schematics or given any information on how the circuit is connected and to what it's connected to no one can help you. You need to post a schematic.

From the extremely vague description I would suggest checking the watch dog timer.

Mike.

Also, are you pulling up MCLR? Decoupling cap?

Some VSM's allow you to simulate your circuit without common connections like the MCLR/OSC, even power supply.