Troj/Optix-Kill copies itself to C:\windows\spool64.exe and C:\windows\winfile.dta.
It adds a registry key in
HKLM\Software\Microsoft\Windows\CurrentVersion\Run
to ensure it is run on system startup.
It also creates the file C:\windows\winstart.bat with instructions to copy winfile.dta to spool64.exe to further its chances of remaining on the system.
While running it will perodically close any anti-virus product, personal firewall or system utility it knows about.