Sure, I'm building XPages on local and I'm debugging them in the client (through the "Preview in Notes" button).
I had to create a new database a started over again. The problem came up again so I was playing with closing / reopenning all tabs in Notes, cleaning the workstation and right-clicking the XPage -> Refresh. I don't know which one of these but once it solved my problem.
FYI: I was reading this article :-)
http://www-01.ibm.com/support/docview.wss?rs=899&uid=swg21327454
Adam