If your old Kaspersky Antivirus just upgraded to Ultra AV, and you perform a virus scan before having restarted your computer, you may encounter the following error message:
The reason for this is that Kaspersky's folders are locked and only accessible to Kaspersky my default. When Kaspersky uninstalled itself to upgrade to Ultra AV, the Kaspersky Lab folder will persist on your computer until your computer has been rebooted.
To solve this issue, you can either reboot your computer, or click on Continue when prompted to provide administrator permissions.