Actionscript broke without touching it

Hi all,

I had something very weird happen. A line of AS2 broke on me without me touching the flash or as file. I went to republish the swf and now get the error:

The class or interface ‘Document’ could not be loaded.

in regards to:

var doc: Document = new Document(1003, 670);

This code is used by an *.as file to dynamically center the website when each page loads/when a browser is scaled. I just don’t understand how the code, which worked before, can just stop working…so perplexed. Any ideas?