is this a known 10.6 issue? something in setup? I ran the test on my computer and it says I should be have the correct hardware.
Can you start a new project and re-add the basemap you used without issue?
I tried a new mxd and it still locks up with basemap (streets)
Well then that narrows it down to your machine or your locale.
You might want to contact Tech Support
I'm having the same issue at my organization, multiple users and computers
I forgot about this.... check it first