Shortly after the start of an instance, like <SID>_[ID]_<HOSTNAME>
with SAP Service Manager on NT Systems, the color of the message server
become grey and priority become normal to unknown.

In a trace file of work process we have (AL11) following lines:
- ABAP/4 Program SAPLTHFB
  Source LTHFBU01   Line 17.
  Error Code RAISE_EXCEPTION
  Module abfunc   20.133.5.1 SAP 98/08/21.
- Function ab_jfune Line 1113.
  Exception condition "NO_SERVER_LIST" raised.

In Systemlog (SM21) :
R/3 System start, SAPSYSTEM [ID], dispatcher PID xxx
Operating system call getservbyname failed (error no. 0 )
Service sapms<SID> not known

ab_jfune NO_SERVER_LIST SAPLTHFB LTHFBU01

There is a missing entry in file service

Stop your instance.
Put an additional entry in the service file like:
sapms<SID> 36[ID]/tcp.