CI does not execute in xampp1,7.3!! Urgent please

[eluser]suba[/eluser]
Dear all,

Last time I used xampp1.7.0 That time CI executes properly.
Just now I have upgraded xampp1.7.3

But my project does not execute . please help .

Urgent please

ERROR
---------

Code:

Fatal error: Class 'Model_sims' not found
in C:\xampp\htdocs\sims\system\libraries\Loader.php on line 184

But Model_sims file is inside Model folder.

This is auto load model