You are crashing with Mozilla Seamonkey or Firfefox and submitted a Bug Report.
As first step run Firefox in the Firefox safemode to be sure that this crash is not related to an addon :
How to run in  the Firefox Safemode

We need a Stack Trace
from this crash if you still crash in the safemode.A stack trace is a list of code executed before the crash.

How To get a Crash ID from The Mozilla Crash Reporter:

Firefox3 and Seamonkey2 should open a crash reporter after you crashed.
Note: That works only for binary builds from, if you are using for example an Ubuntu Firefox, scroll down for the instructions without Crash Reporter.

Be sure that you checked the "Tell Mozilla about the crash" checkbox.

Crash Reporterr Window

Now restart Firefox and enter "about:crashes" as URL and Firefox should open a list of submitted crash reports.

about:crashes list in Firefox

Copy the IDs (1-3) of the submitted reports that are from the crash that you have reported.

Be sure that you don't add an ID of an unrelated crash.
We usually don't need the crash details from the reporter, windows crash details,binary crash dumps or more than 3 crash IDs.

The Crash Reporter doesn't come up after a crash

- Windows

If the crashreporter didn't come up after the crash, you can either try it with disabling the flash plugin in Tools/Add-ons/Plugins

Extension/Plugin Manager

or you can install Flash 10 Beta from
Adobe. Be warned, it's a beta with known problems on a few sites.
The reason behind this is that Flash 9 breaks the Mozilla crash Reporter on windows.

If the Reporter still doesn't come up or you need the flash plugin to get the crash then use the following instructions:

Alternative ways to get a Stack Trace :

- Windows

      How to get a  Stack Trace with Windbg.
      You can also use WinDbg if you get a hang/freeze instead of a crash.
      In that case use the commands "!analyze -v -hang".

- Linux

 Ubunto (source):
   Instructions from the Ubuntu Team

  SuSe (source):
 * Install -debuginfo Packages

 note that to run firefox under a debugger you should use:
 ./ -g -d gdb ./firefox-bin
 not gdb ./firefox