WS2008R2, W-firewall suddenly block DHCP requests (port 67)

Hi,

my windows firewall on server with WS2008R2 suddenly block DHCP requests. It is using as DHCP server. When I turn off firewall, all is working. Everything worked a few years. Dropping is recorded in firewall log:

2014-01-29 08:51:32 DROP UDP 0.0.0.0 255.255.255.255 68 67 390 - - - - - - - RECEIVE

Where can be problem? Some update or some policy? Thank you for response.

kayncz