This is a very strange issue indeed. I don't think I have ever heard of an issue like this.

Sometimes a problem with Firefox may be a result of malware installed on your computer, that you may not be aware of.

You can try these free programs to scan for malware, which work with your existing antivirus software:

• Microsoft Safety Scanner
• MalwareBytes' Anti-Malware
• Anti-Rootkit Utility - TDSSKiller
• AdwCleaner (for more info, see this alternate AdwCleaner download page)
• Hitman Pro
• ESET Online Scanner

Microsoft Security Essentials is a good permanent antivirus for Windows 7/Vista/XP if you don't already have one. Windows 8 has antivirus built-in already.

Further information can be found in the Troubleshoot Firefox issues caused by malware article.

Did this fix your problems? Please report back to us!

In addition, please ensure that you do not have any sort of automated system backup or system restore program setup, as this could be the cause of the issue.

I honestly doubt Malware on campus computers. Even the lab staff has never heard of it. They said that once it is updated it is permanent on my campus username. I seem to be the only person reporting it too. Nobody else has mentioned this—To the lab or to the techs directly. They said it is a per user basis and it should stick if I log into my own account. but nothing could be further from the truth! :(

If this is a campus computer, then the programs most likely restore after a certain period of time. This is usually the case on all publicly accessed computers. Unless you have special permissions from the system administrator on your user account, the server will revert back to the default (apparently Firefox 30.0) on your system.

You should contact your campus IT department.

There could be a workaround for this issue. In most cases, programs are stored either on the computer's local hard drive or a special folder on your campus account servers. You can try installing a version of Firefox 42.0 in a location on your account, where files are not periodically deleted.

Warning: Some IT departments have strict policies about modifying and/or saving programs on your system. Please refer to your terms of service agreement or your system administrator to ensure that you are not violating your ToS by following the steps above.

Two possibilities.

You have both Firefox 42.0 and 30.0 installed.

Your desktop has a method of reverting to a earlier state when Firefox 30.0 was the version used.

Is Firefox program saved to the campus system, or your hard drive?

Download Firefox For All languages And Systems {web link} Save the file. Then;

Using your file browser, open the Programs Folder on your computer.

Windows: C:\Program Files C:\Program Files (x86) Mac: Open the "Applications" folder. Linux: Check your user manual.

Look for, and rename any Mozilla or Firefox folders by adding .old to them.

After rebooting the computer, run a registry scanner. Then run the installer. If all goes well, remove the OLD folders when you are done.

FredMcD said

Look for, and rename any Mozilla or Firefox folders by adding .old to them. After rebooting the computer, run a registry scanner. Then run the installer. If all goes well, remove the OLD folders when you are done.

Anybody following this, Do be careful on renaming any Mozilla or Firefox related folders you find as your Profiles (where your settings like Bookmarks, passwords etc are) is in a separate place from the Firefox program folder.

Have over time asked Fred to word this better as it can be damaging if not careful.