WMI Provider Host stopping

Hi;

I've got four brand new dells. All running Vista Business; all now with SP1.

And all of them with the same problem - a box pops up and tells me that the
"WMI Provider Host has stopped working". Don't know what it does; but it'd
been like this for about a week. I hoped that SP1 would sort it out, but I
downloaded that last night, and it's no go. There's a hotfix for this very
problem on Microsoft's site - I've installed it, to no avail.

Can anyone offer any advice?

Thanks

Tim