If possible try removing all your other USB devices apart from the the wireless USB adapter.
I think the PC allocates resources to each USB device (although over a hundred can be connected at one time) but the actual ports are shared between them.
It would be a worthwhile test and should only take a few moments.
Also it may give some of the more techy guys on this forum a bit more of an idea as to what the problem might be.
Worth a try ?