I had the same issue trying to check my email through them also. 1and 1 unfortunately has not optimized it for this type of browser. I have alot of trouble with them when i use google chrome as well. Wish I had better news to tell you, sorry.
Posted from my CrackBerry at wapforums.crackberry.com
Thanks to all for the answers, I just migrated my email work accounts to IMAP in order to use the BB Playbook and have sync 2 days before realizing that 1and1 changed to web 2.0 and doesn�t work on Playbook browser, thats what I call very bad luck!!!!!