The 'CTD' on loading looks like it's simply being caused by the file version of the Fallout4.esm changing from '0.95' to '1.00'. Wrye Bash bitches about this as well. I fixed that, without rolling back the ESM or BA2s, by hex editing the new ESM's header version number back to '0.95'. So, for reference, that also works... EDIT: Also, again for reference, the files that I see being updated are: Main - Fallout4.exe (Version now 1.10.162 - was 1.10.138) - Fallout4.ccc Data - Fallout4.esm (Header version now 1.00 - was 0.95) - Fallout4 - Interface.ba2 - Fallout4 - Materials.ba2 - Fallout4 - Meshes.ba2 - Fallout4 - Startup.ba2 All these files had the same modified time and date stamp this morning (GMT) For those with the knowledge, software and desire to go the hexedit route of the new Fallout4.esm, do the following: 1) Make a backup the Fallout4.esm file. 2) Open Fallout4.esm in you hexeditor of choice. 3) Make the following edits: - On line 00000010 change the offset values as follows... - - Change offset value 0E from '00' to '33' - - Change offset value 0F from '00' to '33' - On line 00000020 change the offset values as follows... - - Change offset value 00 from '80' to '73' These edits will change the header version (viewable in FO4Edit) from 1.00 to 0.95. 4) Save and quit 5) Start Fallout 4 and check. It should now not CTD on the main menu. Normal disclaimers apply for the above. ;)