WinMgmt could not initialize the core parts

XP, SP2, all updates installed.

Have been having odd problems for about a month, and my look at the
event log shows that on bootup "WinMgmt could not initialize the core
parts"

When I am reviewing Services in Admin tools and look for dependencies,
I get an error dialog box that says WMI: Not Found.

I've found all the relevant KB articles, have even found and run
Windiag.vbs.... it's all quite confusing.

That said, WHAT problems will forcing the rebuilding of the WMI
repository cause? I know that I don't have a good backup that
predates the problem. Everything I read about rebuilding it seems to
indicate that it should only be done as a last resort.

I also know that I should keep a copy of the repository before I force
the rebuild.