Web mail inbox sppears blank

We are having problems with the domino web mail, where we log in via IE6, select the mail tab, it doesn’t show any emails or any of the inbox, sent, folders on the left hand side, but every thing else appears to be working eg calender, to-do items. This issue appears to be confined to 3-4 windows profiles and it doesn’t matter which domino account is used to log in. Has anybody had this issue before and if so is there a fix for this problem?