When you are creating a profile, there is certain time limit in which it must be done. I think this is no more than 30 minutes. Anything beyond that and the profile "times out" and will not be saved. Thats when you have to close it and create a new one.
What I usually do is the minimum necessary to get the profile created (first and last name, DOB or DOD, gender and 1 source minimum) and then save it. Once it has been created and saved, then you have time to go back and add further details and sources.