Let me know if this helps. I use the "Import from ArcView Project" command which prompts me for the *.apr file. After selecting the file, I receive the error message. There are 6 different *.apr files in the "zoningMap" folder. Each one produces the same message. This might be notable: if I go "up" one folder to Y:\Projects\Westmoreland, all of the *.apr files import normally.
using windows explorer, by chance are there *.apr files there that don't have the 'copy of...' attached to the name? I suspect that those files originated from a bad copy paste or a drag and drop into a folder that contained the originals. If you have the originals and they work, then I would just ignore/move the 'copy of...' versions to another location and proceed with the good ones.
I suspect that the data and the *.apr have become separated. You can open the *.apr in a text editor and examine it looking for the original locations of the shapefiles (*.shp) and see if the paths that are specified are where they should be. The problem could also be related to a variety of other issues as well, ... if you still have Arcview 3.x, then you can at least determine what the files were if the aforementioned doesn't work. The import only allows you to bring in the first view and set up a dataframe in arcmap it doesn't carry over the functionality of the original project or anything remotely useful. So in brief... examine the project file, locate the files that were used in the project and proceed using those files in ArcMap.
8,760 lines... yikes! Paths to coverages and shapefiles look to be OK. The map has a lot of unique annotation and graphics added and unfortunately will be very time-consuming to replicate.
Is there maybe a log file where I could go to diagnose this further?
to clarify... if you move the project to a new location, you must also move the data as well. the path to the apr and the data must remain in a structure relative to the original locations, or the apr wouldn't open properly nor will you be able to import it