No, it did not come after any scans or software update. In fact the laptop was in sleep mode, as well as one of desktops. This was first noticed on the desktop during web browsing. The message "Using Mozilla firefox. Install Kaspersky Protection extension to increase your level of protection" suddenly appeared. I followed the instructions in KIS console to solve the problem. When I opened the search box to check whether the KIS plug-in was installed in Internet Explorer too, the problem was evident. Yesterday, everything worked perfectly on all three computers ? The computer on which the Kapsersky plug-in was reinstalled was nor restarted or shut down. Why should it be ? There was no restart request. The same problem emerged on the other desktop and laptop too ? However, on the other two PCs, when I clicked on search box in taskbar, it started OK and looked normal for a moment (few seconds) then suddenly reverted to black box. Yes. Have to try and soon will report. No compatibility problems with other software on any of the 3 PCs. It worked well yesterday on all of them, and no other software was installed in the mean time. None of the listed programs (https://support.kaspersky.com/15071?&_ga=2.22876219.1038600017.1580913244-217039999.1576836002#block1) is installed on any of the 3 PCs 6,7 will report.