Recently I've been into building new infrastructure where I have to build sql server 2005 daily and change the configurations every now and then, so had a chance to look at each minute details/errors etc.
Here are some issues I faced and the solutions I found:
1) We can rename the cluster service account even after installation but need to take care of the following:
a) Make sure the new service account is part of system administrators group on both the nodes
b) Go to here: run "gpedit.msc" -> windows settings-> security settings -> local policies->user rights assignment
c) check your cluster service account is part of most of those listed there like
logon as a service
logon as a batch
create a pagefile
create global objects etc.
2) When AWE is enabled, make sure sql service account is added to "lock pages in memory" on both the nodes, adding it to only one node results in issues while failing over to the next node
3) When configuring MSDTC as a seperate group in failover cluster
a) configure MSDTC IP first with no dependencies
b) Then MSDTC network name with ip as dependency
c) Then MSDTC disk with no dependency
d) MSDTC with all the above as dependencies