This sounds like a preference corruption rather than a file corruption issue.
You may have a look at the hints, Move the folder and Working with the AIPrefs/Adobe Illustrator Prefs file
But if some files has been corrupted, you may try the instructions here:
The second one describes a different, specific issue, but basically the method is the same.
Thank you for your post Jacob. I tried removing the aiprefs file and letting Illustrator make a new one, but that did not make any changes to the error message associated with trying to open newly made files. I didn't try moving the objects in the AI folder and instead decided to try 'flatten transparency' under the object menu. Lo and behold it worked. I guess there was transparency in the Origin files; however, I still do not understand why this issue has just started up after a month of working with these files.
You are welcome, D. Often it is impossible to know what actually happened, and luckily unnecessary in a case like this.
But how did you open the file(s) so you could make the change? According to the OP that was impossible.