recently i encountered the similar problem when the EL connector came off.
the display went blank and the MC was still running and sending data/cmd to the LCD (which changes the settings due to wrong sequence of data/cmd). only way out was to reinitialise the display only. i have repeated and confirmed this.

in your case, i suspect your supply is not adequatly designed in terms of capacity, connections and filtering. pls, look into it.

is this happening, when you move to other rooms also ? sometimes it may be a problem with a faulty flourecent fixture.

in any case, it is a good practice to have a well designed psu.