Try File > Adobe PDF Presets > High Quality Print. This is the best setting for desk-top ink-jet printers.
Thanks, but that's precisely what I've done though! I'm sending the files to a professional 4 color digital press and they are saying that they are not hi-res enough. I just don't get it!?
Ah - for professional presses, they should be able to tell you want they want. If not try PDF/X-4
This assumes you've set up the graphics etc correctly in InDesign!
By the way – have you checked your links and is your pre-flight (found at the bottom) green or red?
The more I think about it the more I'm convinced your images are not linked (have been moved). Look in the Links Panel. If there's a red triangle with a question mark against the images this confirms. You need to relink by double clicking on the question mark, which opens the Finder (or equivalent on Windows) navigate to where your images are and select one. If the images are all in one folder, by selecting one all the others will be linked at the same time.
Hope this works!
You should go to the link panel and check if each image has an effective resolution between 240 and 300ppi (not dpi!).
When you take image to use in InDesign, you should save them first on your disk, and import them via File > Place …
When you have raster images like photos, take PSD as file type in RGB.
When you have graphics, like charts or diagrams or drawings, use AI or PDF/X-4.
Avoid embedding images into InDesign as it will increase the file size of the INDD file. If an INDD file increases over 2GB you will have a good chance to corrupt the file so that you can't use it anymore.
PDF export lets you downsample images that have too much resolution, but will never upsample images.
If your InDesign file is 2 GB it sounds like you are either embedding images or cutting and pasting. If you place images (Edit>Place), your InDesign file will be easier to handle and you can quickly check the resolution of each image in the links info panel.
You can also use the Preflight panel to check resolution and flag images below a set threshold. Preflight will find pasted images below the the limit, while the links panel will not give you any info on a pasted image.