hello Goffen, at the moment this is an english-speaking forum only. would it be possible to rephrase and explain your problem in english, so that more contributors can understand it? this will make it much easier to come up with a solution for your issue. thank you for your understanding!

courtesy of google translate:
hei Goffen, i øyeblikket er dette en engelsk-talende forumet. ville det være mulig å omformulere og forklare problemet på engelsk, slik at flere bidragsytere kan forstå det? Dette vil gjøre det mye lettere å komme opp med en løsning for problemet ditt. Takk for din forståelse!

Many site issues can be caused by corrupt cookies or cache. In order to try to fix these problems, the first step is to clear both cookies and the cache. Note: This will temporarily log you out of all sites you're logged in to. To clear cache and cookies do the following:

1. Go to Firefox > History > Clear recent history or (if no Firefox button is shown) go to Tools > Clear recent history.
2. Under "Time range to clear", select "Everything".
3. Now, click the arrow next to Details to toggle the Details list active.
4. From the details list, check Cache and Cookies and uncheck everything else.
5. Now click the Clear now button.

Further information can be found in the Clear your cache, history and other personal information in Firefox article.

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Please note that the Mozilla support forums are supported in many different languages. If you find the one in your language, you may experience better communication.

Start Firefox in Safe Mode to check if one of the extensions (Firefox/Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Firefox/Tools > Add-ons > Appearance).

• Do NOT click the Reset button on the Safe Mode start window.

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes