User Agent: Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Win64; x64; Trident/5.0; .NET CLR 2.0.50727; SLCC2; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; .NET4.0C) Steps to reproduce: Using Firefox 7.0.1 on Windows 7. After first starting up, the buttons work. They become inactive when I do the following: 1. Log into Twitter (one of my home page tabs); or 2. Add a new tab. When I do this the buttons don't disappear, they just become inactive. I tried the following fixes (discovered on the forums): 1. Restarted Firefox in Safe Mode (addons disabled) - problem persisted; 2. Deleted localstore.rdf and restarted Firefox - problem persisted; 3. Disabled the theme I had downloaded and returned to the default 7.0.1 theme - problem persisted; 4. Disabled the Personas extension and restarted - problem persisted.
In Control Panel\Appearance and Personalization\Display, is your DPI setting set to normal? Could you try using an older verison of Firefox to see if the problem goes away?
I have a similar issue. It's harder to make the buttons disappear, but it has happened a few times in the past week. I do have my DPI setting set to 125% (Medium), and I'm running FF 8.0 on Windows 7. I don't recall seeing the issue on Firefox 7 personally, and it's definitely been recent so I am fairly confident in saying FF6 and previous were fine.
Update from Allen: This turned out to be a one-day glitch. I don't know... it was one of those days. Maybe it was related to the little glitches I was having with my DSL service - I can't tell. In any case, everything went back to working normally.