USB-UIRT works on one machine, not on another

Hi, hopefully someone has some ideas.
On my laptop my USB-UIRT works perfectly.
However when I move it to my HTPC it shows up as a registered device in my USB device list but :
1) The red light is not blinking in response to IR reception
2) Girder 4 is unable to connect to the device.
Same drivers on both system (latest from website)
Any ideas? This worked on my old HTPC.. Its odd that it shows as a device but is exhibiting these issues and only on this machine.
Thanks!
John-
On my laptop my USB-UIRT works perfectly.
However when I move it to my HTPC it shows up as a registered device in my USB device list but :
1) The red light is not blinking in response to IR reception
2) Girder 4 is unable to connect to the device.
Same drivers on both system (latest from website)
Any ideas? This worked on my old HTPC.. Its odd that it shows as a device but is exhibiting these issues and only on this machine.
Thanks!
John-