We're sorry to hear that your Firefox seems to be crashing when you open it. Please perform the following steps to give us a crash report ID that helps us find out more about the cause of the crash.

1. Press the following shortcut to get a Run window: [Windows] + [R]. This should bring up a window that contains a text field.
2. In that text field, enter %APPDATA% and press Enter. An explorer window should open.
3. From that explorer window, double-click on the Mozilla folder, then double-click on Firefox and then on Crash reports. Double-click on submitted.
4. Now, you should see a list of files that contain reports. Go to View > Arrange Icons by > Modified to get the most recent files at the top of the window.
5. Open the most recent 5 files with a text editor and copy the IDs.
6. Paste each ID with bp- into the reply window on the forums.

Thanks in advance!

You can find more information and troubleshooting steps in the Troubleshoot Firefox crashes (closing or quitting unexpectedly) article.

After unistalling and reinstalling, I tried with CCleaner (nothing happened)

I unistalled again and finally I tried with an elder FireFox version (23.0)

The following codes are from the actual installed version 23.0

bp-98668ec9-ccfe-4256-aac7-876322130919

bp-38c78083-6146-4bd7-9730-773f32130919

bp-2ab478e0-65ef-44d6-b137-863762130919

bp-6c410b9d-293b-4688-8d76-ee0182130919

bp-95b7ac65-c636-44bb-b6b9-733832130919

And this codes are from 24.0 that I just installed again

bp-bf491084-0035-44d5-afff-4c9a82130919

bp-cd07d131-a7e8-4d63-bce6-96eca2130919

bp-6b1ba4ad-632a-4bf3-ba6b-1f87d2130919

bp-e2134e1f-4206-4c0b-82cb-eca8a2130919

bp-899d1bb3-3c83-4d2b-93e9-8d1562130919

Thank you very much

this looks like an issue with hardware acceleration - please try updating your graphics driver (here is the latest version that should work for your configuration: www.geforce.com/drivers/results/66701).
in case this doesn't solve the issue, please press the shift key while you're attempting to launch firefox in order to bring it up in safemode. in the dialog window that opens select "continue in safemode" and then disable hardware acceleration under firefox > options > advanced > general.

Definitelly you saved me...

...and now I feel myself a bit like a fool...

Thanks, thanks and one thousand times thanks.

you're very welcome :))