ASP. NET 2.0, trouble again

Event:
Aspnet_wp.exe (PID: 2128) stopped unexpectedly.

Failed to execute the request because the ASP. Net Process identity does not have read permissions to the Global Assembly Cache. Error: 0x80131902

Failed to initialize the appdomain:/lm/w3svc/8/root

Exception: system. configuration. configurationerrorsexception
Message: exception of Type 'System. configuration. configurationerrorsexception 'was thrown.
Stacktrace: At system. Web. configuration. errorruntimeconfig. errorconfigrecord. system. configuration. Internal. iinternalconfigrecord. getlkgsection (string configkey)
At system. Web. configuration. runtimeconfiglkg. getsectionobject (string sectionname)
At system. Web. configuration. runtimeconfig. getsection (string sectionname, type, resultsindex index)
At system. Web. configuration. runtimeconfig. get_hostingenvironment ()
At system. Web. Hosting. hostingenvironment. startmonitoringforidletimeout ()
At system. Web. Hosting. hostingenvironment. initialize (applicationmanager appmanager, iapplicationhost apphost, iconfigmappathfactory configmappathfactory, hostingenvironmentparameters hostingparameters)
At system. Web. Hosting. hostingenvironment. initialize (applicationmanager appmanager, iapplicationhost apphost, iconfigmappathfactory configmappathfactory, hostingenvironmentparameters hostingparameters)
At system. Web. Hosting. applicationmanager. createappdomainwithhostingenvironment (string appid, iapplicationhost apphost, hostingenvironmentparameters hostingparameters)
At system. Web. Hosting. applicationmanager. createappdomainwithhostingenvironmentandreporterrors (string appid, iapplicationhost apphost, hostingenvironmentparameters hostingparameters)

Today, I was confused by ASP. NET again.
The server is a win2kserver with. Net framework1.1.4322 installed and runs properly. Currently,. Net framework2.0.50727 is installed.Server application unavailableError.The Web application you are attempting to access on this web server is currently unavailable. Please hit the "refresh" button in your web browser to retry your request.I really don't understand.