dw,
I hope that you followed recommended procedure for removal of Norton. Unless you do it right, it will haunt your computer system for a long time to come.
SNDMon.exe is a process associated with Norton Antivirus application from Symantec. This process should not be removed to ensure that your system security is not breached. However, if you completely remove Norton, then it can be taken out.
PS: Yes, Norton does cause a lot of "mess"