Restricted Content (on SUBMIT) January cook-off

when I pressed submit button ,I got redirected to home page and a box came up, showing “Restricted Content” and it was happening even when i pressed submit button 7 minutes after my last submission for same problem, i mean, i think it did not happened because of immediate successive submission trial. what was the problem i was not able to submit it and the contest ended ? (my last submission was 16 minutes before the contest ended and i was trying to submit in those 16 min but this problem occurred every time i tried)

i have met the same problem!how to solve ?