Please update to the latest version; http://getfirefox.com

Are you really still using Firefox 3.5.2 from 4 years ago?
Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.1.2) Gecko/20090729 Firefox/3.5.2

If you think you are using a newer version, your UserAgent string in Firefox is probably messed up by another program that you installed.
http://en.wikipedia.org/wiki/User_Agent

type about:config in the URL bar and hit Enter
If you see the warning, you can confirm that you want to access that page.
Filter = general.useragent.
Right-click the preferences that are bold, one line at a time, and select Reset.
Then restart Firefox

If you are purposely using that old version, you should update to the latest release version - Firefox 22.0 and see if that solves your crashes. If the latest version doesn't stop those crashes at least you'll have Crash Reporter ID's to help us help you solve your issues.

Looks like a corrupted user agent because I don't think that Firefox 3.5 can work with Flash 111.8 versions.

See also:

• http://kb.mozillazine.org/Firefox_crashes
• https://support.mozilla.org/kb/Firefox+crashes

If you have submitted crash reports in the current Firefox 22 release then please post the IDs of one or more recent crash reports that have a "bp-" prefix:

• bp-xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx

You can find the IDs of the submitted crash reports on the about:crashes page.

• You can open the about:crashes page via the location bar, like you open a website, or open the crash reports page via "Help > Troubleshooting Information".

See:

• http://kb.mozillazine.org/Mozilla_Crash_Reporter
• https://support.mozilla.org/kb/Mozilla+Crash+Reporter