>This fixed it - but I don't really understand why. The location it pointed to was a valid path, and I had full rights, but as soon as I changed the path to another location, everything worked.<

Well, it is simple:
VFP 6.0 (or prior) opens its resource file exclusively in private datasession (so you do not see it as open file)
Try this:

Start an instance of the VFP environment - open toolbars, order them, size and move the command window, open some projects.
Close the VFP environment and reopen it - all your settings are remembered!

But... open another copy of VFP environment - and you'll see that it do not have access to the resource file! - and all your settings are not applied to this second instance of VFP.

Note that this is not the same in VFP 7.0 - there the resource file is open with shared access :) (thanks God, it's christmass! ;)