I just heard back again from Staples, which says "You need only accept cookies from Staples.com in order to use our website.

"I have researched the issue of cookies with Firefox 3.6.13 and found that this version came with security enhancements which have been noted to interfere with the use of cookies. You may wish to review the documentation for Firefox 3.6.13 and, if necessary, to use an alternative browser such as Internet Explorer when ordering via Staples.com."

Unfortunately Staples did not elaborate on what "security enhancement" interferes. Anyone have any idea? Should I reinstall an earlier version?

I had the same problem too. My troubleshooting steps were to try in safe mode, which didn't work, and then a new profile, which did. So it was possibly something in my profile blocking it. I cleared the cache, and staples.com now works.

OK, I created a new separate profile but I still get rejected by Staples unless I use the default setting under Privacy which is called "Remember history" OR if I select "Use custom settings for history" I must check the box marked accept all cookies. I can do that within my default profile. Any other ideas?

I suppose I could maintain a separate profile just for staples.com, set to accept all cookies, but it seems to me telling my default profile to accept cookies from staples.com should be sufficient. I think staples must be demanding I accept some other cookies (3rd party ones) via their site, though they (now) deny that.

I see cookies from staples.com and www4.staples.com if I click the login link (button).