Would it be possible in future upgrades to change the admin login to wpadmin or something similar?
Plugins were giving me a "cannot load ../wp-admin/options-general.php?page=xxxx.php" error. Collapsing Categories was doing this. I set up a login for Rob Felty, who released the plugin, to help me troubleshoot. Worked great for him. I set up a temp pwd for my admin login for him to try, and he got the same error that I'd been getting with the admin login. So I had to set up a special login to use myself as a work-around for this.
I have multiple websites, and get the same error on all of them, and with different plugins. I downloaded a new copy of WP and set up a brand new temp site, but got the same error.
Several years ago I was using an admin directory in my websites. It was causing erros, and my web host told me they use admin at the server level, and suggested I change it to "myadmin." That worked fine.
The WP admin login may be conflicting with some servers configurations. If it could be changed to wpadmin, this would probably stop the conflict.