This one is probably for Arcana to have a look into but whats the error code. Like a 404 is the unknown page code. You might want to find out your IP address (go to whatsmyip.com) or something like that and PM Arcana and he might be able to look through the logs to see what the error code the server is dishing up.
I get quite a few errors from this site too - maybe 1 in 50 page hits or so but I just reload page and its all ok again. I have put it down to transfer volume since some of the maps are very large and other people might be looking at something and loading the server.
I have also noted that if you fetch pages too fast it stops you. But most of the time you cant see that.