I have a small tower running Oracle 10.2.0.3 on CentOS4 under my desk that I use as a personal sandbox for playing with Oracle so I'm not always futzing with developer instances. This was where I first played with ASM, etc. However, I rarely actually use this machine from day-to-day.
Recently, I needed access to a 10.2.0.3 instance to see if a bug still persisted. All of my production and development instances are on 10.2.0.2, so this box was called to duty. However, when I tried to start up cssd (required for ASM), I got errors referring to configuration files missing. (I'll try to find the exact error if I can dig it up).
The trick is that these files were named based on the server hostname. I had recently renamed this box to fall in line with our internal policy of naming servers after Thomas the Tank Engine characters. So I needed to reset the OCR key to use my new hostname, and all was well again.
Well, all was well after I also installed the updated asmlib RPM for the kernel which I thoughtlessly updated as well.