Nothing works after startup

[Defaes]

This happened out of nowhere!
An hour ago i was playing and the next,nothing works.
Basically the pc starts up normally and as fast as usual,but after that nothing works,not even shutting it off,being forced to do it manually.
I can navigate a little bit on windows explorer and in the start menu,but no program starts at all and it freezes completely at some point (i can only move the cursor and that's it).
Also worth mentioning is that I can't enter safe mode.A few months ago I somehow got the pc stuck in a startup loop.I don't remember what caused it and how i solved it,but as a result I can't enter safe mode anymore because it restarts automatically right when it's about to enter windows and then starts normally.So using safe mode to solve the problem is out of the question.
I also received a message the last time it froze, telling me that microsoft windows is not responding,with the option to end the process,but it did nothing and clicking would display the message again.

My specs are:
-windows 7 ultimate
-I7 4770k
-Msi z87-g45 gaming
-16gb of ddr3 ram in 1600mhz
-Gtx 980
-180gb ssd (windows install)
Nothing is overclocked

 

[DavidJT]

If you press Ctrl+Alt+Del
(those three keys should be held down together)
Then press Start Task manager - is there something
that should not be there and should be stopped ?

 

[Defaes]

Not even the task manager works! It was one of the first things I tried.
Everything loads continuously without any result.

 

[Defaes]

Well,i ended up reinstalling windows which solved the problem.
I guess why this happened will remain a mystery.