Gdlow, your plaint is pretty common among the Workhorse owners. I know mine's done it several times. You'll find other posts about the anomalies of the Actia dash in these forums.
As for a permanent fix, from what I've read there is none... -You can get the Actia reprogrammed, you can loosen/resecure all the plugs, tighten & grease the grounding studs, yadda yadda yadda. I've done all that, but to no avail. I've long since decided not to worry about it (likely because it returns to normal after the brief blackout). I have not heard any complaints about the "new" Actia dash on the '07s with the bigger information center display.