all locally stored on your machine?
properties of the file(s)? the project?
has it always done this?
does it do it with other data?
have you cleared out temporary workspaces etc?
could be a number of things
Data stored local on SSD, tried USB 3.0 stick and external SSD.
On my Laptop with 10.3 it works just fine with the same data!
With 10.5.1 i have this issue regardless of the data type.
Okay, let's keep on working on some other ideas then. Do you have any cached map services in the *.mxd? If so, then it could be a bug (BUG-000107314).
Another option for troubleshooting (in addition to the blog article) is the following:
Open Windows Explorer and go to the following path on your computer and navigate to:
If the CATID folder exists, it will contain files which have an ECFG extension. These files initialize 3rd party extensions that may exist on your computer that were
installed for previous versions of ArcGIS Desktop. If the CATID folder exists, rename the folder as CATID_old. This will disable the extensions.
What is the result?