it gives an error about virus engine not being able to start...
Hi Can you please follow the steps below and review the service state as outlined in steps
1 go to start Control Panel
2. Go to Administration Tools
3. Find services
4. Find COMODO Internet Security Helper Services
5. go to the Log on tab and set your account name and password.
6. Restart you computer.
Follow steps
1 through 4 and review status of service should be set to automatic with your logon username.
go to step 5. and move along to the RECOVERY tab and set first failure to restart service.
Restart computer
Caution do not run the comodo Diagnostics as this will return the settings back to standard and you will have to change the services again.
Hope this works for you
You will not get this issue if you remove windows admin password .