There are two issues:
First: the OP uses an unsupported 3rd party module (simple notifier) that is not compatible with Joomla 2.5. The author of this module is mentioned in a README that can be found within the module.
Second: the OP uses an module, plugin, or CB plugin from a previous version of uddeIM which is not compatible with Joomla 2.5. This problem has been addressed several times in this forum and some links have been given, e.g. to this post:
www.joomlapolis.com/forum/25-uddeim-plugin-and-component/189068-uddeim-for-joomla-25?limit=6&start=24
To be a little bit more technical:
uddeIM uses its own compatibility layer in order to make the main binary compatible to all existing Mambo and Joomla versions. uddeIM 2.5 (and before) checks for a certain Joomla version and falls back to the Joomla 1.5 compatibility layer when the Joomla version has not been recognized.
So in that case the main component (v2.6) recognizes Joomla 2.5 and loads the correct layer, the older module (or whatever) still loads the layer for Joomla 1.5. Since both layer define the same function the following conflict will be shown:
"Fatal error: Cannot redeclare uddeimgetusertz() (previously declared in .../components/com_uddeim/uddeimlib25.php:30) in .../components/com_uddeim/uddeimlib15.php on line 33"
(or a different function, depends what function is executed)
I will try to find a mechanism for uddeIM 2.7 that this problem will be recognized.
