What happens when you try and start iceweasel from command line?
Have you tried using safe mode?
If you can get that far, is there anything in the console?
Code:
root@kali~$ iceweasel -h
Usage: iceweasel [ options ... ] [URL]
where options include:
X11 options
--display=DISPLAY X display to use
--sync Make X calls synchronous
--g-fatal-warnings Make all warnings fatal
Iceweasel options
-h or -help Print this message.
-v or -version Print Iceweasel version.
-P <profile> Start with <profile>.
-migration Start with migration wizard.
-ProfileManager Start with ProfileManager.
-no-remote Do not accept or send remote commands; implies -new-instance.
-new-instance Open new instance, not a new window in running instance.
-UILocale <locale> Start with <locale> resources as UI Locale.
-safe-mode Disables extensions and themes for this session.
-jsconsole Open the Error console.
-browser Open a browser window.
-new-window <url> Open <url> in a new window.
-new-tab <url> Open <url> in a new tab.
-preferences Open Preferences dialog.
-search <term> Search <term> with your default search engine.
-recording <file> Record drawing for a given URL.
-recording-output <file> Specify destination file for a drawing recording.
-setDefaultBrowser Set this app as the default browser.
root@kali~$ iceweasel -safe-mode
root@kali~$ iceweasel -jsconsole
Rules Failed: [Exception... "Component returned failure code: 0x80520006 (NS_ERROR_FILE_TARGET_DOES_NOT_EXIST) [nsILocalFile.isDirectory]" nsresult: "0x80520006 (NS_ERROR_FILE_TARGET_DOES_NOT_EXIST)" location: "JS frame :: chrome://https-everywhere/content/code/HTTPSRules.js :: RuleWriter.getRuleDir :: line 240" data: no]
FoxyProxy settingsDir: /root/.mozilla/firefox/s2boo9xp.default/foxyproxy.xml
Could not check applicable rules for https://check.torproject.org/?TorButton=true#0.99853988781757560.5776748471197128
Could not check applicable rules for chrome://browser/content/browser.xul
root@kali~$