A few days ago my game stopped loading from the SKSE launcher, despite making no changes in the days prior.
I searched for similar problems and followed various advice to verify game cache, run as admin etc but still received the Steam Application Load Error P:0000065432 when attempting to load from the SKSE launcher. Skyrim would still load from the TESV launcher but as I use Sky UI this was not acceptable.
Using Nexus Mod Manager (which I used to install it) I uninstalled SKSE and searched for any residual SKSE files before installing again following Gopher's video guide. My game is now running as it should so it would appear that some form of conflict arose; possibly from a Steam update which I have set to automatic?