Try impersonating the administrator to see if the problem still exists. This error is due to insufficient rights by the user.

>Thank you for your help,
>I did the change to the file bu now I gte the following error :
>Server Error in '/GiftExch2' Application.
>
>Access to the path "C:\WINDOWS\Microsoft.NET\Framework\v1.0.3705\Temporary ASP.NET Files\MyApp\af5a1504\1c47bfc7\hash.web" is denied.
>
>What am I doing wrong?
>
>Thank you again,
>Christian