Python function terminated unexpectedly...

Hi,

I have very strange problem. Without any reason I cannot open my Calibre and I'm getting a message:

Python function terminated unexpectedly
MemoryLoadLibrary0 failed loading PyQt5\QWidgets.pyd (Error Code: 1)

I unistall my previous Calibre and reinstall again. It didn't help.
Later I uninstall everything connect with Calibre from User\Name\AppData
and still I'm getting the same message.
I don't have completely any idea how to fix this problem.
Please, help me to solve this issue.:bigcry:
Thanks in advance !!!!