License logging service problems

I have a domain in mixed-mode with 2 w2k DCs and 1 NT4 BDC.

After upgrading the DCs with SP4 and internet explorer 6 (without warnings), the BDC and all other NT servers started to log the event 213 in application log stating that the license logging service on the PDC can’t be contacted. The network connection between the servers is good (as it was before the sp4); in addition, SAM replication between PDC emulator and BDC works without problems.

Someone may help me?