I've seen a number of related, almost the same topics on this. I have wordpress freshly installed (v. 2.0.3).
Can see for yourself ...
No plugins (that's what seemed to cause it in most people's cases) except for the database backup turned on (well, that's not even on now). If I save the source, and remove the leading line and view it in the browser, then it's OK. Any ideas how to get rid of the leading line or how it's getting in there? Anyone else have this issue with 2.0.3? Searches have only drummed up similar problems. Most solutions appear to be plugin related.