You need to either post the actual links or separate the report numbers and dates. Can only seem to get the first one working after a few tries of what is the report number.

First one https://crash-stats.mozilla.com/report/index/ac64ab02-d672-43e0-aead-f1a552110819

It has two Bugzilla reports connected to it for reading.

  680418 RESOLVED DUPLICATE Cannot start Firefox after v6 update. Crashes and won't start, even in Safe Mode.
  670542 VERIFIED FIXED Crash in nsStandardURL::SchemeIs or nsSimpleURI::SchemeIs mainly close to startup, with a random .cpl or .dll filename in stack (malware-related)

Basically says that crash report and perhaps the others were due to trojan on your system. They changed an underlying function that the malware was using so now Firefox may crash. You need to update your antivirus definitions and scan the system and hope it catches it.

See https://support.mozilla.com/en-US/forums/contributors/707453

for the past 3 days, my firefox keeps crashing..when i'm not even at my computer...is there a problem going on with a recent u pdate?

dawn: The first crash report (linked above by James) shows
ID: ac64ab02-d672-43e0-aead-f1a552110819
Signature: nsStandardURL::SchemeIs (char const*, int*)

That crash report links to two related bugs that indicate that your Firefox 6 crashes are caused by a trojan horse program (malware) installed on your computer.

Even though Firefox 5 works fine, you need to remove the trojan for your online safety. See Troubleshoot Firefox issues caused by malware for suggestions on getting rid of malware.

I have 'up-to-date' virus protection as well regularly run Malwarebytes and nothing was picked up by those tools...which is why I posted to this site to begin with. After your reply, I began searching for reputable other 'online' virus scans and one of them did pick up an infection. Amazing that so many don't see it and lead consumers to think there is not a virus/malware issue. The only scanner that found them was Symantec's online free scanner and they get you because then to remove what it had found, you have to uninstall your current product and buy, download and install theirs. I've already paid for a year of protection...and I hate using the Symantec tools as they make my system come to a screeching halt by taking too much in system resources. I'll keep looking for a reputable free tool that will remove the malware.

Thanks so much!

The person who filed Bug 680418 (which is listed as a related bug on your crash report) just posted this comment to the bug report yesterday:
After a little bit of work, the folks at spywareinfoforum.com were able to help. ( http://www.spywareinfoforum.com/index.php?/topic/132436-malware-effecting-firefox-v6-cant-start-even-in-safe-mode/ )
...so, you could try visiting that forum to see if they can help you, too.

After a grueling 14 hours of repeated scanning/removing infected files, deleting unused user accounts and pulling out my hair, I am finally up and running with Firefox 6.0. Thanks so much Alice!

Hey, that's great!

Could you explain more what solved the problem (did you visit a particular security forum or run a specific malware removal tool?) If a particular post led you to the solution, could you mark it as "solves it"? When a question and answer is marked as solved, other people with the same problem will find it easier. Thanks!

Also, you should get more information about what you can do to protect yourself online, if you haven't done so already, at one of the forums recommended in the article Troubleshoot Firefox issues caused by malware.