Thank you.
Im not using third part anti-virus software, Im on Win10 with bult-in Windows Defender.
However for test, I turned off Defender but Reaper still crashing when I try to load Helix VST
UPDATE
Problem solved!
Before I installed Nativ1.8, first I removed previous version (1.7) and everything with name line6 from Windows >Control Panel> Remove Programs.
Also I removed every line with "line6" in name from windows registry (I don't know if it was necessary or not)
And Reaper stoped crashing at last