I’m sorry but we cannot help because we haven’t a clue how they connect to the internet and to WordPress.com and which browsers and versions of them they use.
Please have those with WordPress.com accounts post into this thread and provide screenshots. They can use http://snag.gy/ to share screenshots so Staff can examine what’s going on. I’ll tag this thread for a Staff follow-up. Please subscribe to the thread so you are notified when they respond and please be patient while waiting.