I have several thoughts.
First, are you running a modern firmware?
Second, push for an RMA.
Third - I have [rarely] seen issues when using independent supply rails (particulary when fed from seperate UPs or a UPS and a different type of supply) where they develop small differences between each other.
The last one I had to deal with was a leakage between the phase and ground lines causing the power supplies in the kit to explode (and I mean explode). You can also get small differences in phase between the two supplies.
To test if this remote case is the one affecting you - unplug one of the redundant power supplies and see if the issue happens again.
I have also [rarely] seen issues where the supplied power factor is getting too out of control (would really like it to be above 0.9). This is more typical in factory environments that run heavy inductive loads. A poor factor factor affects switch mode power supplies.
To test this one you would probably need to get an electrical engineer in (not an electrician). They'll need proper kit to measure this. They can also check your dual power rails to check they are correctly in phase with each other and that you are not experiencing any significant earh leakage. Ideally you really need to do the measurements over a longer period of time, like a week. That is because these problems can be transient in an environment and being caused by other things happening (such as large inductive motors starting up).