Looks like the system is compromised. In other works maybe the viruses you have/had corrupted the system.
Here is what I suggest, download the Kaspersky Rescue Disk ISO Image and assign it to the CD/DVD and temporarily change the Guest OS type to Linux (or you may have to temporarily remove the USB controller from the VM) so as not to have mouse tracking issue while booting a Windows VM from Linux. (Don't forget to change back the Guest OS type when done (or add back the USB controller when done.) Boot from the ISO Image and once at the KRD Desktop update the virus signatures and then scan and repair the system. Then reboot back to Windows and see if you get a normal Windows Desktop. If you do then you can install an AntiVirus program per the manufactures installation directions.
BTW Make sure you make a backup of the VM before doing anything.