It is a clean installation. A installed v5 about 3-4 weeks ago. Before I installed v5, I removed older version via Windows Add or remove programs and drove through CCleaner for leftovers. (I usually remove all programs via Revo Uninstaller but it didn´t listed Comodo IS ■■■ installed program so I used Windows uninstaller).
My OS is Windows 7 64-bit and Comodo IS (64-bit version) product version: 5.0.162636.1135 and it says that Virus Signature Database Version: 0 ???
go to program files → comodo → CIS → repair → right click on bases.cav and select copy then go back on folder and select scanners, right click and select paste when it asks you to over right select yes. Reboot. Then try to update. If it will not let you past do this procedure in safe mode. Let me know if it works.
I done this in normal mode (it let me past that file in scanners folder) but it doesn´t repaired problem. Comodo is still saying: “Update failed. Antivirus engine is not initialized!”. And database version still remains in 0.