This is from a Microsoft support rep that has been working with me on these issues for quite a while now.  I know a lot of people have reported these problems, so I felt it worthwhile to spread the news:

"Microsoft has now found the root cause of this problem to be the IIS ADSI provider. Essentially, if you have a process with more than one thread and two threads access IIS 6.0 at the same time, then this issue occurs.  This problem is likely to occur for the SharePoint Timer service (OWSTimer.exe) in Microsoft Office SharePoint Server 2007. When this occurs, you may find that:

• In SharePoint Server 2007, tasks that are scheduled do not run.
• When you try to manage IIS 6.0 by using Server Manager, you receive a blank page, or you receive the following error message: "the path specified cannot be used at this time".

The Event ID's 7076, 6398 and 6432 and memory error messages described above will also be recorded in the Application Event Logs. Microsoft now has a KB article describing this problem http://support.microsoft.com/?id=946517 along with details of the fix and how to obtain it. This fix is not a SharePoint fix so you should be able to install the fix regardless of what Service Pack level you are running."