Error: Couldn't open server log file "d:\inetpub\wwwroot\oobe.ch\logs\W3SVC5090\ex240420.log" : Permission denied

Setup ('C:\awstats\wwwroot\cgi-bin/awstats.oobe.ch.conf' file, web server or permissions) may be wrong.
Check config file, permissions and AWStats documentation (in 'docs' directory).