Hi Robin,
There is absolutely nothing to worry about if you are opening Adagio Time&Billing from another Adagio program and getting a /t error message. The reason is that if you start Time&Billing version 6.5 from another program, a /t parameter that gets sent to maintain the sign-on date is not recognized - because T&B6.5 is an old version that doesn't recognize the feature.
If you start Time&Billing from a shortcut, rather than from another program, you should see that all works OK.
The Time&Billing 8.0A upgrade allows this date parameter to be recognized, so the error will no longer occur after installing the upgrade.