Try download
www.lineage2.ro/hehehe/system.ace rename your old system folder with system_old, put the downloaded one as system folder and try start lineage2.exe again, if still same problem do a check files, press it 4-5 times, after update finished, press Start see if it works.
If still doesn't work check your firewall, disable it, put l2 to safe list for your antivirus, and make sure it runs with administrator account, while doing this, delete gameguard folder from system folder and then start lineage2.exe press check files 4-5 times til it starts updating with a new gameguard folder, after update finished, press start, should work.
Good Luck.