This must be a V5000 or V3001R with dual power supplies and you have Maintenance Alerts turned on.
Go to Reports/System Data/ Power supply status. .what does that say???
You may have a power suplly starting to go bad... in this case, the entire unit must be swapped out.
To shut off Maintenance Alerts for users, go to User Configuration, click on User, then unclick
"Receive Maintenance Alerts"