I have several ASP.Net applications that write errors and login details to a specific key in the event log.
The key is created OK but the users don't have permission to write to the logs, instead the events all go to the generic Application log.
After some searching I found this article: http://forums.techarena.in/server-security/85026.htm
Which basically says to change the CustomSD DWORD value under the key with the application name and add (A;;0x0002;;;AU) - this gives permission to write to the event log for all authenticated users.