Here's an update of my situation after trying everybody's suggestions:
1. Started in safe mode, ran a Windows system restore. Got the "Couldn't load XPCOM" error message.
2. Tried LIMPET235's suggestion by following instructions at
http://kb.mozillazine.org/Browser_will_ ... c_problems and Firefox still will not start. And I do not get the XPCOM error now.
3. Tried starting Firefox with Avast disabled. No success.
@Brummelchen:
You wrote,
if firefox crashes but offers itself no crash-rep go here:
"C:\ProgramData\Microsoft\Windows\WER"
in some sub-folder staring with "firefox..." there exist a DMP file to analyse - zip and upload!
There are several WER files with crash reports. Do you mean I should upload these files on this forum for analysis?
@Brummelchen: there are the usual one-man computer shops in my area. I may have to call around and see if anybody can handle this sticky issue. I'm getting desperate and am thinking about going to Safari. Chrome and IE are out of the question, as Chrome especially is a spy plaform.
Question: what should be the setting for my AppData\Roaming\Mozilla\Firefox\profiles.ini file ? Is the code I'm currently using (below) correct? This is actually for the replacement profile I created, then moved certain recommended files and folders over to it. All I changed was the filename in the last line.
[General]
StartWithLastProfile=1
[Profile0]
Name=default
IsRelative=1
Path=Profiles/2cntswth.default