Try changing your settings here about:preferences#advanced. Paste this into your browser. Disable "Search for text when you start typing".

Thanks. That option was already un-checked. Any other suggestions?

While your cursor is in a basic form control like the one I'm typing in right now, the Find bar should not be triggered unless you use Ctrl+f. (Ctrl+g or the F3 function key will "Find Again")

If your cursor is outside of a form control, as would be common when you reload a page unless the page moves the cursor into a control, then the / key will open a stripped down "Quick Find" bar, but normally the setting mentioned in the first reply would prevent other keys from triggering the Find bar.

Does this problem occur on every page, or are there particular websites where you notice this?

If you haven't already, could you test in Firefox's Safe Mode? In its Safe Mode, Firefox temporarily deactivates extensions, hardware acceleration, and some other advanced features to help you assess whether these are causing the problem.

If Firefox is not running: Hold down the Shift key when starting Firefox.

If Firefox is running: You can restart Firefox in Safe Mode using either:

• "3-bar" menu button > "?" button > Restart with Add-ons Disabled
• Help menu > Restart with Add-ons Disabled

and OK the restart.

Both scenarios: A small dialog should appear. Click "Start in Safe Mode" (not Refresh).

Any improvement? (More info: Diagnose Firefox issues using Troubleshoot Mode)

Thanks, it seems like it's a spyware issue: Genius Box.

I don't know that one, but if it is a keylogger, that might explain the strange behavior. In case you need some cleaning suggestions, see: Troubleshoot Firefox issues caused by malware.

Thanks, I am going to have to try that because I already tried two other malware softwares and it is still happening :/