Wanted to post this because I could not find help on the internet and I solved the issue. Hopefully, this will help someone else.

When I tried to log in to my dnn site I received the error message: " Login Failed, remember that Passwords are case sensitive".

I knew the passwords were correct because I had logged in an hour before.

If I tried to register as a new user in order to do a password hack(because I thought something just might have happened to the password), I receive this error in Firefox: "The page you are trying to view cannot be shown because it uses an invalid or unsupported form of compression".

After researching the EventLog table I eventually figured out that the SQL database had reached the maximum size limit because I had loaded about 80,000 users into the database and the database size limit was set to 250 MB.

This is an obsure error because I do not exactly know why it would say the password is incorrect simply because the database limit was reached.

The fix is to either purge the EventLog or to increase the maximum database size. I chose to increase the maximum database size to 350 MB in my particular case. If you have the ability to increase the maximum database size, then I would suggest that as the first option so that the database integrity is not accidently broken by deleting table rows manually.