error 0x769484fd when shutting down

[Ed]

I can not shut down my laptop; the next error is shown:

"The instruction in 0x769484fd references ti menory on 0x00000000. The
memory could not be read."
Click accept to end the program.

In the background there is shown "explorer.exe does not allow to shut down
the equipment" and "explorer.exe-application error"

I am using windows vista home basic.

I thought the problem was the explorer, so I installed the new version 8,
but problem continues, I also installed service pack1 and did not work.