Not sure that's your problem, but that might be :
1) You're editing a draft version of your content,
2) You press submit, ez calls a workflow and crashes in the middle (have a look a the apache's log, you might find something)
3) When you arrive back to edit, it offers you the choice between reediting this draft version or create a new one Obvioulsy, as it is still a draft version, you can't see it from the collaboration page. Go to your drafts on the back office, you might understand better what's going on.
I'm developing an event, believe me, workflows are a pain to debug. Good luck.
