Hi Jeeves.
Thankyou for your interest in my problem.
The weird thing is that, since I posted this thread, the problems have all but vanished. Although, I fear they may return...
To try to answer a few of your questions:
It's the game that crashes, not the entire browser. I use Chrome and haven't tried any other browser yet.
I typically get two kinds of messages. One is like "Top11 is low on memory, please restart the game or contact player support." The other is longer, something like "There was an error. bla bla bla... Thanks for your patience. bla bla bla... If this happens again contact player support."
Often it occurs when I try to load the game, but a few times it also has happened when I'm already inside the game and try to schedule training for the team, or even go to the transfer market.
Best,
Andy