For some reason I’ve been getting issues with applications trying to update themselves, file lock errors will occur. Today it started happening with Steam, it downloaded an update and tried to run but was unable to remove the Steam.exe file stating that it was in use.
I did a bit of googling and found that this may occur if the Application Experience service is disabled, of which it was. Once I set it to “Manual” and started the service, Steam could update correctly with any file lock errors.
As for how this was disabled, I have no idea but I believe it may have been an SSD guide or a guide on how to disable non-essential Windows 7 services.