Ok, so I found a [temporary] fix. at this website: http://wordpress.org/support/topic/279132?replies=90 I found a fix that worked for me. As it states below, though, it makes Admin run slightly slow.

6. Add define( 'CONCATENATE_SCRIPTS', false ); near the top of wp-config.php. That would make WordPress admin run slower, so you can try removing it in a few days and testing again (this would eliminate any stale network cache)

Does anyone have any idea what causes this problem and how to avoid it happening again? Does anyone even read this forum any more anyway...?