Cannot redeclare class ci_exceptions... on line 27

[eluser]Unknown[/eluser]
I don't know if it is a bug, but after upgrade to codeigniter 1.7.2 I get this message on several pages that works fine with v. 1.7

Fatal error: Cannot redeclare class ci_exceptions in /home/tgp/webhost/xyz/system/libraries/Exceptions.php on line 27

I found that may be is a bad programing technic for my own, but the sistem should show me the show_error('message').

I have to disable all the show_error on my pages to avoid this.

How can I fix it to works ok???