Message: Cannot open log for source 'ExceptionManagerInternalException'. You may not have write access.
Came across this message when trying to write to the event log using Microsoft.ApplicationBlocks.ExceptionManagement.dll in the Infopath (IFS) form codebehind. However, if you are an administrator of the box (web server where this is running on), you won't have a problem writing to the event log. Since we cannot grant all users administrator rights, that option is out.
Solution: by default, a sharepoint site uses impersonation. Use the SPSecurity class:
As a side note, do not mess with the existing settings in web.config of the sharepoint site. Taking out impersonate="true" messed up our BDC and other things....