Skyrim randomly closed

I have the USP installed (unofficial Skyrim patch).
As I was taking over Fort Greenwall I got the achievement but then as soon as that popped up the game just closed suddenly. No error message, nothing. It just closed fully.
I checked task manager and it's not there (Nor is anything to do with Skyrim at all). Steam still thinks it's running though so I have to force close my computer now. I have 2 mods installed and active: Multiple Followers Mod Lite and Resurrection (And USP), neither of which I have had trouble with before. No DLC's active, just installed but I disabled them until I have finished the main game.
It's not to do with my computer as this is the first time it's happened. Now the game will not load and steam will not close. I was just wondering if anyone thinks they know what happened because I don't want to recreate it as it is very annoying.
I'm going to restart my computer (Power switch as steam wont close so my computer can't shutdown normally) and then see what's wrong.
OS: Windows 8.1 64x
Intel Core i3 (Yes, I know not the best..)
Any other specs I'll be happy to give.
Also, I'm using the Windows XBox 360 controller, again, never had any problems with it before.
Restarted. Skyrim now refuses to play. It just keeps force closing on startup when I click play in steam.
Best Answer
When playing on pc, you game can sometimes get ctd (Crash to Desktop) when Skyrim does not have enough available Memory. When this happens the game instantly crashes. The maxmem Property cant be changed in the .ini Files so you need Startup Memory Injectors ect. ENB to resolve this. Or just disable some mods. If your not using mods then you have a potato PC and theres nothing you can do about It.
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Why does my game close out of nowhere?
The game may close, generate an error, or crash during start or during play if your computer is infected by a virus. Important If you already have antivirus software installed, update your antivirus program by installing the latest signature files before you scan your computer for viruses.How do I find out why Skyrim keeps crashing?
The first step in identifying the cause of any crash is to enable logging so that Skyrim will tell you exactly what happened before the game crashed. By looking at what is happening to cause the crash, we can then determine which mod is causing the crash itself. To enable logging, we need to edit your Skyrim. ini file.How do I stop Skyrim from crashing?
Fix: Skyrim Keeps CrashingHow To Fix Skyrim From Crashing Tutorial
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