> On powering it up again, all the NVRAM contents had been
> erased and the system time was reset.

It's the common symptom when kernel mistakenly marched through its
address space writing and littering garbage value.  I have no clue
why it happened this moment though.

> Then I booted to single user and found
> that if I typed moderately quickly, keys would double repeat, instead of ls
> it would be llss and so on. However in singleuser and multiuser text login,
> keys don't endlessly repeat. When I start X they do.

Tohru Nishimura