This can happen if the internal battery on the motherboard hasn’t been changed recently. The DL2032 battery has a lifetime of about 2 or 3 years. This can be purchased at most electronics stores (or camera/watch shops) and can be changed by the user.

After changing the battery, the BIOS will also need to be reset.

Visit http://www.mackie.com/support/FAQ/hdr_detailed.html
and locate these two documents for instructions on this process:
“HDR/MDR Battery Replacement” (PDF)
“HDR BIOS Settings” (PDF)