I have exactly same symptom on my DH61AG when I updated bios from 4x version to version 99.
Looks like DH61BE is not the only board affected with this 99 version and sad thing is that it can't be reverted back to 4x .
When I try to update bios from version 99 to 105 version with F7 key I get an error during flashing process and then system just cycles with rebooting all the time.
Any ideas to get this 99 bios working?
If you don't have warranty anymore (as me) you can try this suggested by Roly3055 in other topic.
Very useful. Actually I don't understand why this intel guy suggests to go to warranty support to everyone.
Who don't have this option (like me) almost have a heart attack.