Some systems become unstable when vista inspirat is installed,
I will advise you to restore your system to another time when your computer was working fine..
This should be done on safe mode, press F8 when computer starts and select: SAFE MODE
To do system restore please try this:
Press Start, All Programs, Accessories, System Tools ----> System Restore Open it and then select a date when your computer was working fine...
then press next
Let the process to be done
Restart your machine normally
This will solve the problem