Windows takes too long to log in, the UI is prone to freezing and crashing, the Start Menu doesn't work anymore, and all Windows Apps don't work

This is now the third time this problem has occured to me.
Yesterday, I wanted to open a pdf document in Edge when suddenly all Windows Apps and Explorer.exe crashed.
That was the sole trigger. Nothing was remotely wrong before that.
But, as I have said, this is not the first time this happend to my Windows. I started attempting all means of fixing this problem (like sfc /scannow and reinstalling all the win. apps, as well as some other methods) you would find when googling this issue, to no avail.
Then, I noticed that the ShellExpcerienceHost was prone to going inactive and seemed to crash or stop working in the TaskManager and EventLog respectively.
I again tried to fix this with the methods several sites recommended (also the reddit posts I found) with no result.
Currently, I am stuck with a ridiculously log-in time (not boot), a broken taskbar, an Explorer that likes to crash or freeze, and no usable Windows App (including the new System Control stuff).
Other programms or performance are not affected.
Now, I am tending to roll back to Windows 7 because I have clearly had enough, but if some of you have a way to fix this, I would be quite delighted.
I just checked the EventLog again to see an ESENT type error concerning svchost with the occuring IDs 454/412 in the category Protocolling/Recovery. Also, svchost is visible at least 10-15 times in taskmgr details tab.
EDIT: I just fixed the problem with this http://answers.microsoft.com/en-us/windows/forum/windows_10-other_settings/settings-doesnt-launch-or-launches-the-store/ec439819-7ee4-4b4d-abdd-35d82e04c55f