Following a couple of departmental redundancies, our policy is to change 'system' passwords to something new. I was asked to modify the Domain Administrator account for my 2003 domain which was also being used as the Cluster Service account. I decided to create a different account clusadmin, and gave it the correct rights as per the MS Knowledgebase article 269229. I stopped the Cluster Service on both nodes, changed the service account and brought up the cluster without issue. I then changed the domain administrator password. Everything went well for four days (about 100 hours) and then all the cluster resources started failing. The error for each service was '9016 DNS signature failed to verify.' The only way I managed to get round the problem was to change the Cluster Service account back to the domain administrator (with the new password), restart the first node, and all came up fine. The second node was then brought up successfully. What could cause this behaviour, after 4 successful days? I gave the clusadmin account all the rights I believe it should have had. Does some backend process run after 100 hours or something that could cause this? Thanks.