That is not answer: because few days before crunch machine work like a charm. So I doubt that drivers is problem.
It sortof could be, since there's been a lot of 'near VLAR' tasks in the last couple of days that get missed by the VlarKill app & possibly, to a lesser extent the rescheduler too, which could be crashing the driver. There are definite improvements in the latest driver that 'appear' to reduce the occurrences of driver crashes, that normally require a machine restart, and tend to exhibit exactly the symptoms you posted.
Eliminating that as a possibility 'properly' before going deeper would be a wise troubleshooting step, followed by checking for accumulated dust * then performing various card stress tests to make sure it hasn't taken Ill.
Jason