have you just tried export>export to PDF? are you trying to just save the file as a PDF?
Are you using something (an image, pdf, etc.) that came from somewhere else?
Often there are hidden processes and scripts in things we get externally and then import. They come from people using different programs, from email programs trying to strip out viruses, the differences between the script for exporting a colored rectangle verses a placed image, RGB and CMYK used in the same document and who knows where else. Typically it gives me this error.
My suggestion: Take anything you didn't make yourself and rasterize it in photoshop, saving it as a TIFF. Re-place it in InDesign and try again.
Don't! This would rasterize every vector and text and this cannot be, what someone wants.
Why not simply export the file? If a problem appaers try to find the page where, by exporting page by page and finding the problematic object.