ebay selling problems

[gotchaeme]

im its free listing day today and i want to add some items ive done this loads before but something is either wrong with my account or my computor because i go on selling page and then i start to sell and then it brings me to the sign in page even though im already signed in so i sign in and then it goes back to sign in and it repeats this and wont let me sell anything , my friend tryed it on his computor and it works so what is my computor doing , is it blocking it some how ? i can buy and bid but cant sell it doesnt make sense and my password is right !
someone please help me as i need to list by them today
thanks