I've never come across this error before and I'm sure its not common, unless you constantly send files somewhere on the planet with a different timezone.

I recently created a snow as2 script for BigStockFlash.com but it got rejected because of a class conflict error. I tested the files again and found nothing was wrong with the files.

I re-packaged the files without modifying the code and sent it through. This time it worked. The only difference was the time I sent it.

Solution
Change your system clock to be the same as the time in the country your sending the files to or wait 24hrs before sending them again,