My Ubuntu worked fine with kernel 4.15.0-23, but after upgrading to new kernel, it often freezes. For example, when I input my password to login or when I click the network settings or something else, the Ubuntu freezes and I can do nothing.
I have tried different version of kernels from 4.15.0-26 to 4.15.0-32, however none of them solve the problem.
It seems that the problem is caused by the nvidia driver because sometimes the system reports a bug about nvidia driver 390. But currently, the kernel 4.15.0-23 works fine and never freezes with the same nvidia driver.