Having got into StumbleUpon at work today, the whole random browsing thing was quite a fun way to waste an hour, I decided to get it setup on my laptop at home. I went to the site, clicked the 'Get StumbleUpon' link and installed the extension, when I restarted the browser I was asked to put in my username and password and, after a short pause to search for the relevant the email, I did so. Firefox immediately vanished. Somewhat perturbed I started it up again, it vanished again. I tried running it from the console and found the following error message:

/usr/bin/firefox: line 159: 16795 Segmentation fault $AOSS $MOZ_PROGRAM $@

Surmising it was something to do with the StumbleUpon extension I started up Firefox in safe mode (at this point I was thankful to have other browsers installed, so I could google for the correct command line option, -safe-mode) and disabled it. Sure enough Firefox then started fine. Since I have almost exactly the same setup on my browser at work (apart from the linux bit) I wondered if it was a problem with setup process in the particular version of the StumbleUpon extension so I tried installing an older version. This produced the same results as before, if the extension was enabled I got a segmentation fault, if it was disabled everything worked fine. I decided it was some sort of conflict with one of my other installed extensions, so switched back to the latest version and started in safe mode then disabled everything except the StumbleUpon extension, aiming to enable my other extensions one at a time to find out which one was causing the issue.

At this point I restarted Firefox and it still produced a segmentation fault. Suddenly it occurred to me - it was a conflict with the theme! I use the Pinball theme rather than the Firefox default, though StumbleUpon was working correctly on my work PC even though that also has the same theme. Anyway, I set my theme back to the default one and restarted Firefox and voila - it all loads up and I'm presented with my StumbleUpon toolbar. I configured the toolbar the way I like it (no search box and in the menu bar) and then tried to enable the Pinball theme once more. This time everything worked without problems. I've not done any deep investigation but I suspect there's some issue between Pinball and one of the fields I turned off in StumbleUpon (which were the search field and the show friends/network/etc fields), or Pinball just doesn't like StumbleUpon in 'toolbar' mode. Either way, it's all working now, and to prove it I'm going to recommend this post