What is wrong with Quartus II?

Of course that's not normal behavior.

I don't think the "Window not responding" problem is necessarily associated with Quartus; it could be an underlying

Windows installation or configuration issue. See for example:

https://answers.microsoft.com/en-us/windows/forum/windows_10-performance-winpc/windows-10-system-unresponsive-programs-not/481e603e-80d5-4374-a147-25478adfec66?auth=1

It is easy to blame an issue on the software that is reporting the problem or appears to have the problem at a superficial

level. But Quartus relies on Windows, and if Windows has an issue, then a number of applications may not work correctly.