There a number of possible causes for your problem:
1. Your logged on as a different user.
When you use impersonation, the aspnet process is running as the user
that was authenticated with the IIS. Since you are running on your own
machin, I presume you use Windows Authentication and the logged on user
is the user that runs the process.
If you are accidentally logged on as a different user with less
privileges and no permission to write to the registry you will see that
message.
2. Your own account permissions has changed.
For the same reason as 1, this can happen if your own account had
permissions to write to the registry but now it doesn't have.
3. Your authentication mode has changed.
If your IIS was set to Windows Authentication, but now it is set to
"Anonymous access", the IIS no longer run under the logged on account.
Instead it runs under the IWAM_<machine name> account which is used to
run the IIS process. As a result, the aspnet process will also run as
the IWAM_... account which is a low privileges account.
To solve your problem I would choose not to use impersonation.
I would instead try to give the ASPNET user (which runs the aspnet
process when you don't use impersonation) specific privileges to the
registry.
But I'm not a security expert, so you should check the implications
carefully before doing it this way.
Yanir
