besides the bug I've read about in the forum:
http://puzzlepicnic.com/community/posts/list/15/945.page about not being able to edit the solution in (for me Chrome) some browsers I encountered another bug.
When I wanted to edit my masyu puzzle I saw instead of my puzzle merely the code behind it, even after refreshing etc. Then I was a bit stupid and tried (without java experience) to fill in 'null' in the code, with the idea of resetting the puzzle, which of course didn't work but completely destroyed the puzzle. (I can still edit the code, though.) Finally I'm not able to delete the puzzle, but that's familiar too: