Quote Originally Posted by sstt1976 View Post
18F2550 with 20MHz xtal, HSPLL, any possible postscaler, any possible DEFINE OSC can't make 1ms into 4ms.
Like I said before, you can't run a 20Mhz xtal into the HSPLL! The PIC is probably running on the backup internal oscillator (add some code to check for the oscillator fail bit and see what it reads back).