I have experienced many problems with various PCs (especially laptops) which fail to connect to the programming device.
I stumbled upon a workaround though:
I discovered that by running the program Chipcat v2.3 first (one of the many programming utilities you can find on the sat sites), the port is somehow always kick-started into life. I just connect the programmer without any card inserted, run chipcat, kick off its pogram function, and let it fail (since there is no card inserted). Then I put my card in and run the utility I really wanted.
This is not necessary for all programmers (eg - the MasteraII and VX-Multi) but is for others (eg my VP2, VP20, PICPro3 and old phoenix).
Chipcat can be found (for example) at Duwgati's excellent site:
http://www.jali.nl/satelliet/satinfo/index.html
Direct link: http://www.satinfo.org/download/ChipCat/chipcat23.zip
Worth a try...??
2old