[TYPO3] Problem uploading 'inc" files

[Lee M. Childress]

I just upgraded to Typo3 4.2.1 last night (love the new back end layout) and
everything seems to be going well since the upgrade except .

 

When I try to upload a file (regardless of the extension), I get the
following error message:

 

1: Fileextension 'inc' not allowed. (tt_content:155:pi_flexform)

 

What did I do wrong, and more importantly, how do I fix it?

 

Thanks!

 

Lee