Try clearing your cache and the Ebay cookies, this can often resolve this type of problem. For details see How to clear the Firefox cache and Clear cookies and site data in Firefox.

If that does not help, check to see if an add-on is causing the problem, for details see Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems.

Thank you Tony, the first part of your suggestions solved the problem.

You're welcome

i have had the same problem since yesterday...tried clearing cache, disabling add ons...still nothing works

Make sure that you do not block cookies for that site.
See http://kb.mozillazine.org/Cookies

If clearing the cookies doesn't help then it is possible that the file cookies.sqlite that stores the cookies is corrupted.

Rename (or delete) cookies.sqlite and cookies.txt, if they exist, in the Profile Folder in case cookies.sqlite got corrupted.

• http://kb.mozillazine.org/Cookies#Removing_cookies

thanks..tried this and still not working?

I have been having this trouble for about four months. I have cleared cache a number of times. I have deleted the cookies.sqlite file. No good. It's not just logging on to Ebay. I can do that. But when I try to bid on an item or use Buy It Now, it takes me to the Sign on screen and keeps looping back to it. I have the same symptoms accessing my Yahoo mail. I can sign on to My Yahoo, but when I try to go to Mail, I get the signon loop. And it did the same thing when I tried to log in to the Firefox Support Forum to post this comment. I am currently using Firefox 4.0b11. And it started happening before I went to the 4.0 beta version. None of this happens using I.E. 8. Help!

Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of the add-ons is causing the problem (switch to the DEFAULT theme: Tools > Add-ons > Themes).

• Don't make any changes on the Safe mode start window.

See:

• Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems

If it does work in Safe-mode then disable all extensions and then try to find which is causing it by enabling one at a time until the problem reappears.

• Use "Disable all add-ons" on the Safe mode start window to disable all extensions.
• Close and restart Firefox after each change via "File > Exit" (Mac: "Firefox > Quit"; Linux: "File > Quit")

Tried Bid on Item on Ebay and access Mail on Yahoo. Does not work in Firefox safe mode. I noticed that when I started safe mode, Firefox 3.6.13 started. This was the version I had before I loaded version 4 beta. It didn't work in that version, either. At least it's consistent.