Stamina/Speed switch stopped working (Z11VN)

[malomas]

I tried to switch from Stamina to Speed mode on my VAIO Z11VN laptop. The standard warning appeared (close applications or you may lose data). I clicked OK but the machine stayed in Stamina mode. I repeated this several times with the same effect.

After rebooting, neither light (Stamina or Speed) is lit and moving the switch no longer has any effect. The Intel video driver appears to be running, which is what I would expect if it is still in Stamina mode.

I tried to reinstall Sony's power management utility but the installation script displays a message saying that it refuses to overwrite a more recent version.

Why might this have happened, and can anybody suggest a solution?

n.b. I haven't installed any new applications recently. It is still running the pre-installed operating system (Vista Business). The system is fully patched and virus scanned. I have also run chkdsk to check for possible disk corruption (no errors found).

[Blencogo]

Are there any devices showing a yellow (!) warning symbol in Device Manager to show they are not correctly installed? Check SFEP is installed under Human Interface Devices.

What version of the nVidia Graphics driver do you have installed?

If both of these are OK then it may be necessary to reinstall the Sony Utilities in order: -

Sony Shared Library

Setting Utility Series

Vaio Original Function Settings

Vaio Event Service

From here: -

http://support.vaio.sony.eu/computing/vaio/downloads/preinstalled/index.aspx?l=en_GB&m=VGN-Z11VN_B

If the problem remains, come back and we will try to think of something else.

[malomas]

Thank you - that helped me find the solution.

The Device Manager told me that the nVidia driver was returning error code 31. Device Manager's own diagnostics were unable to fix this but armed with the error code I was then able to find the solution in Microsoft's knowledge base.

In particular, the Microsoft 'Fix It' troubleshooter can fix this problem.

[Blencogo]

Excellent!!