I'm posting this solution to a problem I have had for over 12 months with connecting my Thrive Tablet via USB to my Windows Vista PC. The PC would report 'Driver not found' and the search for drivers online would go nowhere. Those in the forum familiar with my posts will be aware that I'm visually impaired and the recommended fix for the above problem has been 'Install Windows 7'. Sorry, for me that undertaking is a big ask for me, so I persevered looking for another answer - until today!
I will post the solution on the off chance it may help someone else.
This site has a procedure for another USB Device, and I simply substituted 'wpdmtp.inf' for the one they used.
So the modified instructions I used where (if you have the same problem I had:
Look for 'wpdmtp.inf' and 'wpdmtp.PNF' in your C:\Windows\inf folder.
If missing, go to C:\Windows\System32\DriverStore\FileRepository
Locate Folders with 'wpdmtp' in the first part of the name
Open the most recent wpdmtp Folder
Select the 'wpdmtp.pnf' and 'wpdmtp.inf' files and right-click menu Copy
Open C:\Windows\Inf and paste the files
Now, you will need to install the drivers
Connect your Tablet to PC via USB cable
If you get a pop-up asking to install drivers, select Browse, and enter C:\Windows\Inf as the path OR If that doesn't happen:
Open Device manager under 'Other Devices'
Mine was AT100 - Right-click menu 'Update Driver Software'
Select Browse and enter path C:\Windows\Inf
This should do the trick. I was SO excited having found a solution for this problem, I just HAD to share it Now I can avail myself of the kind offers of forum members to help me root my device. WooHoo!