DHCP randomly not giving out addresses

I have a handful of users that can't get the DHCP server to assign them IP
addresses. The server crashed last night and when users logiged in this
moarning about 20% can't get an IP address. I've had to go around and assign
them one manually.

When I open DHCP to take a look I get this error:

"the dhcp server you specified cannot be located"

The DHCP server stopped working.
A DHCP Server must be authorized in the Active Directory before it can
assign IP Addresses

It shows as being authorized and I can sleect to unauthorize but I get an
error "invalid parameter"

Again, only 20% of users are affected so it must be working and assigned
people IP addresses.

Thanks.


--
Thanks for the help!

This turned out to be a firewall issue - when making a change there was
a typo that somehow affected the routing on the server.