File Upload Class File type problem

[eluser]RJ[/eluser]
I tried changing the file name before initilizing the upload class like this:

Code:

$tmp = substr($_FILES['userfile']['name'], 0,(strpos($_FILES['userfile']['name'],'.')+1));
$_FILES['userfile']['name'] = $tmp . 'txt';

But doesn't work, must be something in the temp name, any thoughts how I can fix this? If I change the files to .txt they upload fine, when they're .log it errors out every time.

Thanks