Hi Leigh,
- Did you make any recent hardware or software changes?
Method 1:
You may try the steps given below and check if it helps.
a. Click Start, type the following path in the Start Search box, and then press ENTER:
%SYSTEMROOT%\Performance\WinSat\DataStore
b. Try to delete everything but the most recent file.
c. Reboot the computer and try doing the re-assessment.
Method 2:
a. Click on start and type cmd and right click on cmd and select Run as an Administrator.
b. Type winsat formal and press Enter.
You can refer to the following article and check.
Note: This aticle applies to Windows 7 also.
You can also refer to the article below for more information on Windows Experience Index.
What is the Windows Experience Index?
Check if there is information in event viewer that might help us in troubleshooting the issue:
What information appears in event logs (Event Viewer)?
Hope this information is helpful.