I'm much more familar with Exchange and the Outlook client, so I'm not sure if it makes sense in this different situation to ask if the user is seeing the same issues at the desktop..also, so I understand, this happens even if the account was fully deleted from BES and added back in? ....since there are different devices involved, each with new activations it doesn't seem like a service book or device issue ..seems like all it could be is something with the BES account on the back end or the user account on the mail server

This is an interesting issue. Again I'm familiar with Outlook, so i don't know if there is a web based client that talks directly to the mail server and bypasses the desktop( and the Blackberry) in your situation..but it would be interesting to see if the issue occurs with a web based client that bypasses the desktop environment and the Blackberry device..