PROBLEM:

I have a Drupal site where TinyMCE goes away after the user uploads an attachment.

STEPS TO REPRODUCE:
- Create a new node.
- Edit the body of the node with some random text Lorem Ipsum blah blah blah.
- Save the node
- Go back and edit the node
- Upload an attachment to the node (example an excel file)
- From now on, whenever you attempt to edit the node the wysiwyg no longer shows up and the page renders differently.

QUESTION:
This is a multi-site where TinyMCE and Attachment uploads seem to be working on all the other sites of the multi-site.

So the question is, how can I begin to troubleshoot this issue and determine what is causing this odd behavior on this specific sub-site of my Drupal multisite? any suggestions?