I have the problem with 2 users on my SP. But none of them has alert. Nobody in the system has any alerts. With my own user I created an alert on a list, and yet the name wasn't reset.
The only hint I received from the client about this issue is that he was "leveraging the user security". And still I'm unable to reproduce the problem.
It is still occurring everyday at the same time like a trigger or timer job is running, but last time I did check, nothing was running at this hour.