I ran into this today too for a site we our migrating to our server. From what I've found so far, I'm not seeing an easy answer. Changing the Database's Collation will only impact new tables and won't affect existing tables, you character based columns will still be using the original collation. When temp tables are created, they (unless otherwise specified) use the Server's default collation and that is where the conflict is occurring (the GetEventLog SP uses a temp table).

I've found a few options but none of them are appealing:

1.) Change the collation of the columns using an Alter TABLE but that would be a ton of work. BAD OPTION.
2.) While you could certainly modify any stored procedures that use temp tables to always set the collation for the temp table, you'd have to redo that process every time you upgrade DNN, BAD OPTION
3.) Change the default collation of the server to match the original collation of that database. This isn't an option for me.
4.) Recreate all the database objects in a new database with the proper collation and then import all your data. This is the best option I've found but would be a pain in the rear. I think I can do this by automatically generating all the script... but still makes me nervous.

Anyone got any better options?