User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0.1) Gecko/20100101 Firefox/4.0.1 Build Identifier: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0.1) Gecko/20100101 Firefox/4.0.1 When you have enough tabs open such that when you use the location bar it suggests something from your open tabs, if you are typing a url beginning with 'm' (e.g. mail.isp.com), you end up with 'hail.isp.com' i.e. h for m letter substitution. This appears to be happening because the initial 'h' in http:// from the tab suggestion is retained, instead of deleted. Why this appears to only happen with m-initial urls is a bit of a mystery. Reproducible: Sometimes Steps to Reproduce: When it starts happening, it stays happening until you close and reopen Firefox. I can't reproduce it exactly, but it happens "most" of the time. My suspicion is: 1. Load up a few tabs 2. Hit ctrl-L or mouse into the title bar 3. Start typing 'mail.something' 4. Check you have enough tabs open that after typing the 'm' above, it suggests a switch to tab. The suggestion should start with http:// 5. BUG: notice the 'h' of http stays there even if you start typing something else Expected Results: The software should not have kept the 'h'. Workarounds exist e.g. either disable switch to tabs (via a plugin) or to do something like accept hail.something.com and go back and make it hmail. then delete the h. Annoying though.

The current bug and bug 599678 are both duplicates of bug 559878.