Hi everyone as this is my first post I’m hoping I’m posting it in the correct place. I am having problems running The Windows System Assessment Tool (WinSAT) which is the software built into Microsoft Windows that provides you with a ‘Subscore’ for all the following:
Processor:, Memory (RAM):, Graphics:, Gaming Graphics:, and finally for Primary Hard Disk: at the end of the test you are then provided with a ‘Base Score’ which is determined by the lowest subscore.
When I have installed ‘Avast Free’ it will run the assessment but at the end of the test ‘Windows Experience Index’ will come up with a fault saying 'The Windows Experience Index for your system could not be computed. Could not measure storage performance. Error: Failed to properly assess the disk. The parameter is incorrect.
Removing Avast (Free Edition) fixed this for me. I tried re-installing and enabling ‘Passive mode’ and disabling shields etc. but nothing fixed it except removing Avast from my Windows 7 PC Computer.
I thought I should report the fault hoping for a possible fix.
Paul 
with a fresh clean install of (Windows 7 Ultimate) x64