Web pages saved with Firefox can't be opened from my file manager (Thunar/VectorLinux) with Firefox. Why is this? I can open them with Opera and other browsers but not Firefox.
What file extension do these files have?
Does it help if you rename them and add a .html file extension?
There are other things that need your attention.
Your above posted system details show two outdated Flash plugin(s).
You should remove them both and update to the latest Flash 10.3 version.
Update the Flash plugin to the latest version.
What happens if you choose Firefox as the application to open those HTML files?
Did you check the file association settings for Firefox (usually firefox %u) ?
When I open an HTM file with Firefox I receive this error message:
File not found Firefox can't find the file at /home/richard/News/Murray.
Note: The path to the file is often abbreviated.
Where do I find the file association settings? In the Firefox menus Edit > Preferences > Applications there is no HTML file type listed.
Do these file names that do not work have spaces in the file name?
You can try to add quotes around the "%u" to see if that helps.