had the same issue but none of the above worked and the adding the HKLM parameters fix did not work either.

We traced it down to someone was over zealous of security and removed the AD Service account group from the Cluster Admin security but did not add the SQL Service accounts back in.

If you remove the AD Group from Cluster admin for SQL 2005, you must add the SQL Service account back in so SQL can connect and cluster can manage the resources. in this case, it couldnt read the IP parameters. makes sense since this is the first parm in the dependency chain.