Disable "open in layers" in Acrobat?

This is just a question, and probably a rookie problem: every single PDF file I download or save as a pdf in Photoshop or Illustrator, when I want to open it again, opens as "Layer 1" rather than as "Background". That means that in every case, if it's an image file that I want to open, examine and close, I have to flatten it first or it will save as a new PSD file rather than as a TIFF(default) or a PDF again. It seems odd to me that an application that doesn't really function in terms of layers, crams layers down my throat when I open its native file type-PDF. I work mainly in Illustrator and Photoshop; I'm not adept at Acrobat, so it's probably happening because I missed some setting or preference. Is this just a "trash the prefs" matter? Any help will be appreciated. I'm on a Mac Powermac G5 2GHz w/ 7GB RAM, running CS3 on OS X 10.5.6


i found this link:
Here you can see a comparison between Excel workbook and excel services.
At the point: unsupported, you'll find the tag "tooltips"
I guess, it's not supported, sry...