Because SAPI 5.1 is a superset of SAPI 5.0, the two versions can coexist on the same machine. But if both SAPI 5.0 and SAPI 5.1 are installed on the same machine, uninstalling either version could damage the other installation and require it to be reinstalled. For this reason, we recommend that you uninstall SAPI 5.0 before installing SAPI 5.1.
When English Office XP and SAPI 5.1 reside on a computer with a non-English version of Windows, removing SAPI 5 or an application which removes SAPI 5 could cause Office Speech to fail. If this occurs, use Office's "Detect and Repair" program.
None of the SAPI 5.1 components or compliance tests were tested with power-managed (OnNow) computers. As long as the system determines that there is application activity, it will not put the system or any devices into the sleeping state. However, if you encounter unexpected performance issues while using power management, OnNow should be disabled.
Occasionally, it can be difficult to uninstall a previous release of the Microsoft Speech SDK 5.0. Subsequently, install the Speech SDK 5.1. Here are two options:
(i) Run the application Regedit.exe. Delete all entries under HKEY_CURRENT_USER\Software\Microsoft\Speech\RecoProfiles\Tokens. Deleting the contents of this registry key removes the speech recognition profiles. Next, install the Speech SDK 5.1.
(ii) If your problem continues, delete the HKEY_CURRENT_USER\Software\Microsoft\Speech and the HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Speech keys.