Yes, it DO (does) reset...

I set portd.0 to toggle on timer1 interrupt and it's been working fine.. (4.2Khz)..(i didnt get rid of those stuffs)

Then I set portd.0 to toggle inside the (if Flag = 1 then...) and it's been toggling in a frequency of 900Hz... It should be also 4Khz....

Well, any idea?

Thanks!