After installing the KB938979 Vista Performance and Compatibility Pack in order to ‘improve the performance and stability of Windows Vista’ – the power to bypass, skip or disable the driver signature signing is imparied. This happens as the “bcdedit -set loadoptions DDISABLE_INTEGRITY_CHECKS” command in 64-bit Windows Vista is altered– in fact the 32-bit Vista does not seem to be affected as yet. Thus, unsigned drivers fail to connect and load, rendering the corresponding hardware useless or faulty. Moreover, lack of a ‘disable driver signing’ feature makes this problem hard to fix up.

Typical symptoms of this problem are that you are faced with a slew of error messages after you have installed the B938979 Vista Performance Update Pack, and restarted your computer. These errors messages can be something similar to –

“Can not connect to low level driver. Please reinstall The Driver under Local system administrator account or try to start driver manually using “Low Level Driver Installation”, or

“Can not load low level device driver. Please restart application”, and so on this sense.

There are not cracks or patches to fix this problem as of now – however, there are a few workaround strategies that you can use.

  • Uninstall KB938979 Vista Performance Update installation. For this, go to Control Panel -> Uninstall Programs, select Installed Updates on the left pane, find Windows Vista (KB938194) and click on Uninstall.
  • However, if this Windows update is crucial for you, you can use another strategy – press F8 on computer startup, and then select “Disable Forced Driver Signing” option to continue booting Vista. This will disable driver signing for that session only, but not permanently, so you will have to do it on every reboot.

You can also try the ReadyDriver Plus for a complete solution.


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