- Delete the black list file on your machine
This way might be useful when you get tired from googling for kaspersky keys or when you just want to enable kaspersky to scan for virus and you don't have time to start searching for keys.
The Black list is a file on your machine that contains list of black listed keys. This file typically is placed in C:\Documents and settings\Users.AllWindows\Application Data\Kaspersky Lab\AVP8\Bases\black.lst in windows XP or in C:\ProgramData\Kaspersky Lab\AVP8\Bases\black.lst in Windows Vista and windows 7.
If you tried to delete that file in normal way "shift+delete", you will get a message saying that you can't delete that file because it is currently in use "protected" so to get around that you will have to boot different OS and delete it from there.
One of the easiest ways to boot another OS, is to try one of Linux live CD and when OS is loaded you can delete. after you boot windows again kasper will say that black lst database is corrupted and so you can get it any old key file that you have used before "already blacklisted" and kasper will be enabled again
N.B: you should think twice before you updated kasper because it will normally restore that black list again from server and the key will be black listed again