Is it possibly a Windows XP Pro Problem?

[ScaleRobotics]

I don't think the 628a is capable of writing to its own memory. So I don't think it is possible for you to use a bootloader for that chip. So what happens if you take this out of your code?

Define LOADER_USED 1

Also, you could try out the sample hex file code on MeLabs website (but it is made for the 4 Mhz crystal that comes with the hardware), just to make sure the hardware is working as you thought. http://melabs.com/doclist.htm#X3

When you define the osc, you must use capitals! DEFINE OSC 20. PBP is proably defaulting to 4 mhz.

Also, the MeLabs example program for that hardware uses PortB.2, like Dave mentioned. Here is their example:

Include "modedefs.bas" ' Mode definitions for Serout
　
loop: Serout PORTB.2,T2400,["Hello",10,13] ' Display "Hello", next line
Pause 500 ' Wait .5 second
Serout PORTB.2,T2400,["World",10,13,10,13] ' Display "World", skip a line
Pause 500 ' Wait .5 second
Goto loop ' Do it forever
End