CryptoTab extension is blocked and I don't know by what. I tried disabling all other extensions with no result. Even uninstalled 360 Antivirus. Same result. The most annoying is always switching to the tab which can be seen in screenshot. CryptoTab FAQ says this about "What can I do if mining is blocked?": "Your security system (antivirus, adblocker and etc. ) probably blocked mining script money.js. You need to add CryptoTab or money.js to whitelist in your security system. Find «exceptions» or «whitelist» item in the menu of your security system and add money.js and Cryptotab.net to it. You can search more information exactly about your antivirus specifics in internet. " BTW, it's working in Google Chrome, which I really don't like using. I want my FFback