Fast User Switching Compatibilty & Terminal Services problem

[MickL]

I've been investigating a problem with a friends pc and found that Fast User Switching Compatibilty & Terminal Services were causing one of the multiple svchost.exe processes as well as the lsass.exe process to constantly take up 99% of the pc's processing power.

I've disabled both services in the Services Console and the processing power is now back to how it should be.

As a result of doing this I realise that the pc won't allow multiple users to be logged on at the same time but its something that my friend can live with.

However, does anyone have any idea what could have caused these services to act in such a way and if there is anyway of re-installing the original files (?) to make it possible to re-enable them?

If the original files can be re-installed, does anyone know which files they are?

Thanks in advance