why?....

[turkuaz]

In the other thread, he was using RA4 to count the pulses.
And I'd be willing to bet this motor and the PIC are on the same power supply.

Yes .You are right. I use RA4 for counting.Is that wrong pin?
I use regulated supply for Pic(5V DC) and motor is connected to same plug (on the wall) but not driven energy from regulated supply that pic use.
some time everything goes good but sometimes occurs this problem.
I use relay to run motor.Pic drive raley than motor running.Motor uses 220Volt AC not pic supply

[skimask]

Yes .You are right. I use RA4 for counting.Is that wrong pin?
I use regulated supply for Pic(5V DC) and motor is connected to same plug (on the wall) but not driven energy from regulated supply that pic use.
some time everything goes good but sometimes occurs this problem.
I use relay to run motor.Pic drive raley than motor running.Motor uses 220Volt AC not pic supply

Got a snubber across the relay coil? Good caps across Vdd and Vss on the PIC? Good pullup on MCLR?
RA4 is only an issue if using it for an output.