Snapshots for domain controllers on Windows prior to version 2012 are definitely a no-go. With version 2012 MS added functionality to detect this. However I didn't try this myself, yet..
In case this is the only DC in your domain, it may (no guarantees) work to revert it to the snapshot. With other DCs in the domain the way to go would either be a fresh installation/promotion or using an AD backup of another DC and restore it to the DC in question after reverting to the snapshot and immediately booting to AD restore mode.
André