User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:12.0) Gecko/20100101 Firefox/12.0 Build ID: 20120420145725 Steps to reproduce: Configured proxy (Squid 3.1.19) with NEGOTIATE and NTLM authentication, auth keepalive off. Order of offered schemes: 1. NTLM 2. NEGOTIATE Actual results: Random re-authentication popup windows shown, if correct data entered - popup appears again, content not downloaded, if i close popup - content is shown normally. When NEGOTIATE is offered as first and keepalive is on - no problems are found. Expected results: Strongest auth mechanism should be chosen and no popups.

It's a dupe of Bug 318253, I think.