Hi there,
what platform are you runnong on? What version of OEM? From your descriotion im guessing that its the management server you cannot start? If so, what happens? If on NT, do you get an 'internal windows error' ?

I found that I got this when I hadnt set up the management service config correctly

Run the configuration assistant, choose Edit configuration parameters and make sure the format of the service field is in the format machineort:sid. Previously I had problems with this and this is what the problem turned out to be.