I am unable to list an item for sale today Ebay keeps asking me to sign in when I already am !

[digital*ghost]

This is a fairly common issue, the only things I can suggest is to clear your cookies and cache, and/or try a different browser. I've had this a couple of times with Firefox, but so far it's never happened with Chrome. 

[quiltsandcrystals]

happened to me too - change your browser - very frustrating!