Okay, try inserting brackets around your OUTP variable this way:

Code:
mainloop:
  FOR LP = 0 TO 9
    READ LP, OUTP
    I2CWRITE SDA, SCL, CHP001, [OUTP]	'WRITE 1's
    PAUSE 250
    I2CWRITE SDA, SCL, CHP010, [OUTP]	'WRITE 10's 
    PAUSE 250
    I2CWRITE SDA, SCL, CHP100, [OUTP]	'WRITE 100's 
    PAUSE 250
  NEXT LP	
Goto mainloop                           'LOGICAL END
I just tried removing the brackets on a short test program I've been playing with and it didn't work right anymore until I put them back.