TerryfromtheToon

@HeyYou, strangely this is the only thing I haven't tried, gonna give it a shot in the morning and will report back.

@subaverage, no, this is where I tried the -len=false command, it didn't work.

Fallout 4 will open the Launcher, but when pressing 'Play' Steam sends a notice that the application is attempting to launch with the '-len' argument, and gives the option to Continue or Cancel. Same thing happens with F4SE. I have 840 hours in the game and this has just started happening. I have un-installed, re-installed. Changed program parameters in Windows to launch as Administrator and run in Windows 7 compatibility mode. I have deleted all INI files and let Steam repair the program. I have tried putting my own arguments in Steam to run with this program. Oh and -len=false doesn't work either' I cannot figure out why this is happening or how to fix it. There are only a few threads out in the wild with this same issue. All of the suggestions in those threads have not worked, and I'm not sure if the OP of those threads ever got their game working. Purging mods doesn't make any difference. The only wayI can get FO4 working is to uninsall then delete the FO4 folder completely then reinstall. Then I can play vanilla (no thanks). As soon as I try with F4SE it crashes again. Frankly i'm stumped and any help would be great. Is there anyone familiar with this issue, know what causes it, and how to fix it?