In order to restore the master database in a SQL Server 2005 cluster(activepassive) I perform the next steps : 1. Identify the node SQL is running 2. Take SQL Server Resource offline 3. Go to the node running SQL and run at command prompt(in the Binn folder) : sqlservr.exe -S tcdpp7xxxxxyyyyyy -m At this point I get this error : " Your SQL Server Installation is either corupt or has been tampered with(Error: Parent iInstance name exceeds maximum length). Please uninstall and rerun setup to correct this error" I am able to connect using sqlcmd using this server name tcdpp7xxxxxyyyyyy but is not working as a sqlservr.exe -S parameter. The other option I tried was to use SQL Configuration Manager and add the -m parameter to the Startup(after taking SQL Server Resource offline). This works but when I try to connect using sqlcmd I get the "only one administrator can connect at this time" error. It looks like the cluster service account is still conecting to SQL Server and I can't open another connection in single-user mode. I stopped the Cluster service but after that I am not able to start the SQL Server anymore... I will appreciate if you have any idea about the "name exceeds maximum length" error and also any information that can help me to solve this issue. Thank You !!!