I just had this issue and called into the TT HELP LINE. - you need to enter the 6 digit ip pin at another area. FIRST TURN OFF YOUR FIREWALL.
Then go to the federal taxes tab, then other tax stiuations, then down to other return info, then the identity protecion pin line, then click on the start/update button - you then follow the insructions to enter the 6 digit ip pin.
IF YOU DON'T TURN OFF YOUR FIREWALL FIRST YOU WILL GET AN ERROR MESSAGE.