firefoxPROXY
It seems that FF has a problem with 403 Access Denied responses from proxies, at least for ssl.google-analytics.com. I've found this post which describes my problem. I'm posting my workaround as an answer, but would also welcome any more information if anyone has it as I can't find anything!
EDIT: Note that the current version of Firefox which is experiencing this issue is 3.0.10
EDIT: Still there for FF 3.5…
Sort of. You can apply lock down settings with mozilla.cfg. This, however, will prevent all users from using locked down features though. Administrators can of course swap in/out the config file at will.
Here's the list of settings we deploy via lock down. It's a K-12 environment, so your needs will likely vary.
//
lockPref("app.update.auto", false);
lockPref("app.update.enabled", false);
lockPref("app.update.silent", true);
lockPref("browser.cache.disk.capacity", 1000);
lockPref("browser.download.useDownloadDir", false);
lockPref("browser.rights.3.shown", true);
lockPref("browser.search.update", false);
lockPref("browser.shell.checkDefaultBrowser", false);
lockPref("extensions.update.enabled", false);
lockPref("plugin.default_plugin_disabled", false);
lockPref("plugin.scan.plid.all", true);
lockPref("plugins.hide_infobar_for_missing_plugin", true);
lockPref("profile.allow_automigration", false);
lockPref("signon.prefillForms", false);
lockPref("signon.rememberSignons", false);
lockPref("startup.homepage_override_url", "");
lockPref("startup.homepage_welcome_url", "");
lockPref("xpinstall.enabled", false);
lockPref("xpinstall.whitelist.required", true);
Also see the locked config settings on to the official Mozilla.org docs.
A few thoughts come to mind, which may be of varying utility.
if you open about:config in the browser bar, there's a preference called browser.fullscreen.autohide which is set to true by default. If you toggle it to false, the tabs and address/url bar won't disappear anymore. You can change that option globally with a script or GPO (a GPO with no script would require one of the custom FF adm templates out there) to eliminate some of the user panic caused by full screen mode. Menu bar will still disappear, but users who think a webpage made their computer disappear probably don't use that much anyway.
The Firefox keyconfig add-on. You could use it to change the full screen to Ctrl-Alt-Shift-F or disable it all together. Honestly, I haven't done an enterprise Firefox roll out in forever, so I'm not sure how easy, difficult, or completely impossible it is to modify a setting in an add-on/extension via script or GPO.
The function called to go into fullscreen is BrowserFullScreen();, which seems like it could be useful if you wanted to punch something up to intercept or block that function call.
User education and/or abuse. True wisdom comes only through suffering. Make your users wise beyond their years. I'm rather partial to the below picture, but your users may be less intimidated by you, or not have a phobia about burning to death. YMMV.
Best Answer
I found Bug 492558 that sounds like exactly what you are running into. I'd recommend adding yourself to the CC list for the bug and clicking the "vote" link next to the priority.