Windows Index dropped

Hi. Since I purchased my current computer back in August 2011, I have had a score of 6.4. However yesterday I received an error on the system tray stating that the Nvidia driver had failed and I should reinstall it. Well I went through the directions and now I have a 5.1...

It doesn't really mean much to me but with that big of a drop I wanted to see if I did it right.

Scores:
Processor 7.4
Memory (RAM) 6.7
Graphics 6.4
Gaming Graphics 5.1 (formerly 6.6)
Primary Hard Disk 6.5

Computer Specs:
Intel Core i7-2630QM quad core processor
750GB 7200RPM SATA hard drive
Memory 8GB DDR3 1333MHz SDRAM
Windows 7 Home Premium 64 bit OS
Nvidia GeForce GT 540M 1GB dedicated graphics with Optimus (Also have the integrated Graphics Card.. whatever that is)
DirectX 11.0.