Problem on Win IIS: "Class not found".

[eluser]Unknown[/eluser]
So, I've got an application that I've ran successfully on a staging server that uses MS IIS.

So far, so good.

Now, I'm trying to deploy it to production, which has (supposedly) the same configuration, and I'm getting an error I've never seen before:

Fatal error: Class 'xxx' not found in E:\http\xxx\xxx\system\core\Loader.php on line 303

Basically, the core loader is loading up a model I have requested in my controller, and it fails on the line where it instantiates the class;
from what I can tell, the application is finding the file (so it doesn't appear to be a path problem ), and reading in the source ( the error message actually shows some of the source as its being loaded ), but the class definition is not created within the application.

It doesn't really matter "what" the model is, as long as its a model that is being loaded through Loader. Basically, this failure occurs whenever I try to load any model..

Any ideas?

[eluser]InsiteFX[/eluser]
If your on a live server why is it pointing to E: ?

Check your base_url in config.php

[eluser]Unknown[/eluser]
Thats the absolute file path; its not the URL. CI can find everything just fine; but loading the classes themselves seems to not "stick" the class definition into the current namespace.

*Note, my guess is its the E drive because of some configuration on the production host, I don't control this environment unfortunately

[eluser]InsiteFX[/eluser]
Check your file names not sure with IIS but some servers are case sensitive.