cached mode will delay the reconciliation, not stop it (normally)
user should be able to trigger the reconcile now (menu--messages--menu button and reconcile now.
is that still working for them?
also, look for a certain message that wasn't removed/changed/moved through reconciliation on the HandHeld and open the message.
Was it received using BlackBerry Sercure or Unkown Secure?
Is the BBserver installed on a seperate server? Check mapi32.dll files on Exchange server and on BBserver (bbserver mapi version should be at least equal.