I have a map service that fails to initialize when its set to use a dedicated instance pool (min 1, max 3) and starts no problem when switched to using the shared instance pool. Any ideas why this would be the case would be appreciated.
When you try to start the service as a dedicated instance, are there any log entries that coincide with that time?
Have you checked on the CPU and Memory on the server while the mapservice is being published as a dedicated service would consume more RAM as compared to a shared service and maybe you are getting close to server limits?