Workstation Z420 switches itself off although in operation mode

Hi all,

we have a Z 420 workstation (3 years old)  controlling a spectrometer working the whole day. Since some months we have the problem that the workstation sometimes switches itself off although the spectrometer is measuring (with all consequences like data loss).

We tried a BIOS update ((J61-0391) with no success.

Is that a known problem and are there any suggestions to resolve it?

Thanks a lot.