I have a Handheld Programmer and a Keyfob Programmer. I am experiencing problems connecting to PC with Windows XP, and with updating the programmer code.
XP Service Pack 2 has re-introduced polling of the parallel port so that new printers can be detected when PC is running. This causes the PC adapter to loose control of the port, causing communications problems. A fix can be downloaded from this link
Another problem can be fast Dual or Quad core processors - we are working on a fix for this.