Lock up, but not deadlock?

Is there a possibility that there will be a lock in a transaction, but it is not a deadlock?
I have N functions (about 20-25) interacting in a system. They are like: setUserOnline(...) setUserOffline(...) setServerOnline(...) and so forth. We have found out that there are sometimes deadlocks. We have solved this by trying again 5 times. Most oftenly it works after the first retry, and worst case has been 2 so far. Anyway, is there a possibility that these functions (we have NO manual lock obtaining in them) cause lockups that is not called deadlocks but has to be solved anyway? Like an UPDATE waiting for another statement in another function, but it's not a circular thingy (a.k.a deadlock). Thanks for any help!

Daniel Åkerud