Have I put a bigger drive in your machine No I have not.
Only USB devices is mouse,removed it but that did not help.
I tried that also, no luck
This and another problem (Cannot create system restore), which I also posted on here, arose after running Tune up Utilities 2011 software I accepted lots of suggestions from it to clean and speed up my PC, maybe a coincidence but Im now afraid to use it again.
I did a clean install of windows yesterday and now PC is doing all it should, have created a restore point no problem.