Change computer name == messed up task scheduler!

I recently changed my computer name, and have since found that all the
scheduled tasks I set up have been messed up. Each task has the account to
use, and within this is the old computer name.

I'm surprised Vista didn't update things like this when the name was
changed, but anyhow.

To make matters worse, the scheduler complains about "the specified account
is not valid" for a whole bunch of my tasks in a custom subfolder within the
Scheduler, but then I find that all these tasks are hidden away now and I
can't see them to edit them!!

I also can't find where on the system the config files (perhaps XML) are
stored to do this manually.

I've also tried deleting the whole subfolder in the Scheduler, but it
complains that I must first delete all tasks in the folder.... but I can't
see them to be able to do that!

I've also done View > Show Hidden Tasks, but nothing shows up.

Any idea why MS should make this so difficult??

Mike