I would suggest, first of all, not hooking it into your computer. USB Passthroughs - and a variety of other non-standard hardware - can destroy a computer's motherboard or power supply or even the data on a hard drive in a big hurry. I'm a computer tech, and I build and service computers for a living. Many people do use their passthroughs on their computers without any difficulties, certainly, but it only takes one small issue to create a huge problem. You can buy USB hubs that don't require a connection to your computer that can serve as a power source for your PT, and there are a variety of other AC to USB adapters out there can provide the power and connections you need without jeopardizing your computer. I picked up three AC-to-USB connectors on eBay the other day for about $6 each.
If your PT isn't working, there is a possibility that it is not getting enough power for some reason from your computer's USB port. If this is the case, then fiddling with it can cause a short that would damage your system significantly. If you search the forums, you'll find a number of people who've damaged or ruined their computers via a PT connection.
Here's one link for reference.
http://www.e-cigarette-forum.com/forum/ecigarette-technical-issues/9213-fried-my-work-computer.html
Can you provide some additional details so maybe we can figure out what might be going on?
Sherrick