Internal 500 Server Error The server encountered an internal error

Can anyone help me with this one?

I attempted to change the categories.php file to list in alphabetical order, it didn’t work so I deleted the codesuggested on the help pages.

Now when I click on the Categories subpanel on the Dashboard I get the above error.

I have reverted to the original categories.php file in the 2.6 download and still the same error.

I am using the Devart theme and all other subpanels on the dashboard are working fine.

Any ideas what might be causing the problem?

bcull