I've been having a very strange issue with flash (CS4 by the way) and I can fix the problem, but I would really like to know what is causing it. I have a site I've made with a bunch of different files loading into a master page. I noticed that one of the files on a lower level appeared to have a white splotch on a higher level that would cover up part of an image. By rearranging the levels of the files I was able to narrow it down to two files which apparently had the white splotches in them. But if I look in those files, there is no graphic or drawing or anything there. I tried adding a black box on a new layer that I put below all of the other layers, and I can't see any white splotch that way either. So I started deleting things in the library and testing what causes the splotch to disappear.
I narrowed it down to a set of buttons I have floating in the middle of the stage. They're all at 0% alpha, stacked up in about the same location. There is no stray white nonsense in the buttons, so I don't know where its coming from. I can fix the issue by just moving them off the stage, but I cannot figure out what is causing the issue and I don't want to accidentally have this happen again. I didn't know if, for whatever reason, stacking up 20-30 buttons all with 0% alpha would cause this kind of glitch or something.
Also, if I delete one of the files and view the site, the remaining white 'splotch' is not a portion of the one I see when both files are there. When only one file is visible, just a tiny part of the splotch is there, so for whatever reason, when both files are there they seem to build upon one another and make the white spot larger (I don't get it). Its also strange because I have several other files that have invisible buttons stacked up in the same way, but those do not cause this white spot to appear. Its always the same two files.
Hopefully that makes some kind of sense, its kind of a weird thing to describe, but perhaps someone else has had the same issue?