Does Yii (Or Php Itself?) Have Some Sort Of Class Cache? How Do I Clean It?

Hi,

I'm literally freaking out. I have a php file called Whatever.php in the "components" folder which contains a class definition for class Whatever which is an application component.

I have modified and saved the file. Now when I call the application from a browser, the old version is being executed. I am 100% positive about this. I can vim the php file on the server and see it's my new version, but then I refresh teh page from the browser, I look at the application.log, and the newly logged traces are clearly from the old version. That is, the old version is being run NOW.

Does Yii have some sort of php class caching mechanism of its own that may have a bug? If not, does PHP itself?

What else could be causing PHP to "remember" an old version of a php file that has already been overwritten?

I had never observed such a thing before.

thanks in advance
m.