Resending signature issue; does this happen to all users or select users? From my personal experience if it happens to select users it usually tends to be 2 reasons:
1. Stored password in OS Go to start run type rundll32.exe keymgr.dll, KRShowKeyMgr
2. User has laptop and has NIC and wireless enabled. The dual connection sometimes causes slow link and causes outlook to connect via outlook anywhere. You can disable the option in the Outlook Anywhere setting about slow links.