Error while trying to run project: Unable to start debugging on the web server

[Moshe]

I used to be able to debug an asp.net application.
In the last few days I am getting
"Error while trying to run project: Unable to start debugging on the
web server. Click help for more information"

I followed all the suggestion there (other then "Manually attach") and
it did not help.
I addes all the IUSER and IWAN users to debuggers.
I register aspnetispai.dll

I am using framework v1.1.4322.
The application runs OK without debugging.

What else can it be?

Need your help
Thanks