I am having Corporate email through BES plus Gmail Accounts on BB. Currently the model is 8100, however this issue was also present when I had old model.
My Corporate Email "Desktop" will send an email, the green ticks appear, but after few seconds the Red Cross appears alongwith message. I have to ask the guy managing BES to resend Service Book and the error is gone. This happens again and again sometime after 5-6 days and sometimes less than this. During error period the Gmail Account works perfectly. Also when these out going emails are blocked the "Service Book Not Found" error and attachment downlad errors also occur for corporate emails only.
Someone has told me that this error occurs when someone link BB to laptop through Desktop Manager.