What is line 90 of the web.config. That will give you the best place to
look.

In general, there are a couple of things that can cause the problems you
are describing.

1. You have subwebs that are serving sites.
2. The sites have a corrupt ASP.NET temporary folder.

Without more information on your server set up, I doubt you will get
much more help than this generic information.

one thing I would do is figure out which Microsoft patch munged up your
server, as it was most likely a Microsoft patch that did it (things
don't "just happen", so the root cause, if you have not changed
anything, is a server update).

once you know the cause, you can search for support, as there is likely
a "if you build your web apps like X, this patch might".

Peace and Grace,

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