Hello,

I've not heard of FF 25 causing this particular issue but I have heard of other programs such as ZoneAlarm and QTranslate causing the problem on specific versions of Firefox.

For example these two previous support requests: here and here.

The best way to test it is probably to boot into Windows Safe Mode with Networking. Then see if you have the same issue in Firefox. If the issue doesn't appear in Windows Safe Mode then you can be pretty sure that another application (most likely security software) is causing the problem.

If the issue still appears in Windows Safe Mode then I suggest trying a Firefox Reset:

Refresh Firefox - reset add-ons and settings

This will return Firefox to default settings. Your bookmarks and history will be saved but you will need to reinstall your add-ons.

update: i tried safemode for win, normal mode for FF, ctrl+c works! so for sure it is some apps that is installed on my pc, amazingly i realised that chrome and IE have the same issue! while other apps such as word, sticky note or golden dict doesn't have any issue! what could be shared between chrome, IE and ff?

there it is! the Goldendict version 1.0.1! in it's preferences and hotkey section has a item : use the following keyword to translate a word from clipboard which by default is ctrl+c+c and when it is checked ctrl+c doesn't work in any browser! as soon as you uncheck this option everything works just fine!

Great! I'm glad you got it sorted.

Thanks for using Firefox. :)

meanwhile it wasn't necessary to use startup check, just use taskmanager and stop process and check for apps running one by one