Some more information that might be helpful. I found that in any browser I choose, if I go to the administrator page and just keep hitting the refresh/reload button, I eventually see the problem happen. In Chrome it seems to happen about half the time (but with no consistent pattern) and in Firefox it happens about 20% of the time.
When the problem happens, I see something like this:

- CalAdmin1.jpg (13.18 KiB) Viewed 427 times
When the screen is displayed properly, I see this:

- CalAdmin2.png (16.7 KiB) Viewed 426 times
So it appears that some script does not run properly to adjust the contents of the userRightsListUnitsDropDown div (and other divs also are not updated as well).
Questions that can benefit the larger community should be asked in a public forum, not a private message.