usb not recognized (plaese help)

I have a miniduino (ATmega 328) with Prolific usb chip. I bought it two weeks ago. it works well. But when a week I use, it not recognized by my windows7. :-[

Device type: Universal Serial Bus controllers Manufacturer:(Standard USB Host Controller) Location: Port_#0001.Hub_#0001

Devica Status: Windows has stopped this device because it has reported problems. (Code 43)

any ideas for this problem? it's very helpful :D... thanks before..

Is there a USB hub between the miniduino and the computer?

Twice we have had computers lose track of the drivers for the FTDI usb chip and had a terrible time getting the proper drivers reinstalled. This finally did the job:

THIS IS NOT THE SOLUTION FOR YOUR PROBLEM! It is the solution for other people's problem.

A similar solution probably is available from and for Prolific parts