Hi BLACKRAT,
Thanks for coming back to us.
A new contract wouldn't effect how you access the emails so it would just be coincidence that it's happened around the same time.
As you're accessing the mail through a browser, can you try what Ravenstar has suggested?
It's also worth deleting the cache, cookies and browser history and making sure you are typing in the web address instead of going on a bookmark to see if this helps.
Keep us posted with how you get on.
Thanks,