As Ars Technica first reported on Friday, users on social media started complaining earlier this week that YouTube ads were triggering their anti-virus software. Specifically, the software was recognizing a script from a service called CoinHive. The script was originally released as a sort of altruistic idea that would allow sites to make a little extra income by putting a visitor’s CPU processing power to use by mining a cryptocurrency called Monero. This could be used ethically as long as a site notifies its visitors of what’s happening and doesn’t get so greedy with the CPU usage that it crashes a visitor’s computer. In the case of YouTube’s ads running the script, they were reportedly using up to 80 percent of the CPU and neither YouTube nor the user were told what was happening.