I have not experienced this but I don't think I've had that many tabs open in a single group. I would suspect that the frequent pauses while scrolling through the tabs are an effect of having so many open. Many websites are like programs in terms of the amount of resources they demand of your computer. Having 74 open at once is likely to cause problems.

It also looks like you have a number of toolbars installed. Some like the Ask toolbar have been known to cause problems. You should try starting in Safe Mode which will temporarily disable all of those add-ons. See if the problem goes away. Instructions for doing that are in the article, Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems.

I have the same problem here. It appeared after upgrading to firefox 11.0 on Ubuntu 10.04. I usually have dozens of open tabs and keep them between firefox sessions and never experienced the problem.

The fact that it could be not good idea to keep so many open tabs is irrelevant to the fact that this is a bug. I would not argue if firefox crashed due to memory problems but this behaviour does not make sense, no matter how many tabs you open.

Moreover, i can force the tabs to show again on tab bar if i follow the next procedure:

• For the first tab, go to it (through drop down list) and open a link in a new tab -> The hidden first tab now appears on tab bar
• For the last tab, go to last tab - 1, open a link in a new tab (now the last tab is the recently opened tab), then close it -> now the hidden last tab appears as last on tab bar

I am experiencing exactly what alexx is saying, but in 64bit Windows 7. There is definitely a bug here if alexx is experiencing the same in Ubuntu. I even closed some of the tabs and also grouped tabs, same problem exists. Also, I might add that the additional steps outlined by alexx also taken by me works temporarily and the issue comes back almost immediately. However, I have now reduced the amount of tabs opened to 63 and so far have not seen the problem come back. I wish there was a way to report this bug more directly; if there is a way I don't know about it. Like alexx I have also experienced this problem after upgrading to the latest Firefox release. Maybe there is an upper limit set in software by mistake or a check that is not functioning correctly with the tabulation code?

Afterthought... I did uninstall the ask toolbar today and that's when the tabs seem to be working, but I'll give it some time and report back. That is the only toolbar I had installed. I hate toolbars or anything that adds a background process except an anti-virus. I only installed the ask toolbar because I wanted the dictionary part of it.

Can you access the first tab via Alt+1 and the last tab via Alt+9 ?

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

• Don't make any changes on the Safe mode start window.
• https://support.mozilla.org/kb/Safe+Mode

• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

I have this too!

To get to the last tab I have to:

1. scroll across to last visible tab (last -1)
2. click on next tab over (last -2)
3. try scrolling again (sort of works)
4. click on the small faction of the last tab, that is now visible

My first tab is now a blank page, so I don't need to scroll to it.

I develop web systems using Firefox as the test-bed, but I am slowly moving over to Chrome to actually browse the internet because of this!!