A week after Google has unveiled a new plug-in that reportedly allows businesses using Microsoft Outlook to switch to Google Apps, there seems to arise some compatibility issues now.

Microsoft on its blog said that the Google’s Apps Sync software has a ‘serious bug/flaw’ that could disable some of the capabilities of Outlook.

According to Dev Balasubramanian, Outlook Product Manager, the installation of the Google Apps Sync plug-in would modify the registry key which will disable Windows Desktop search from indexing and providing search functionality for Outlook data. This would disable Outlook’s ability to search any Outlook data.

He said that just uninstalling the plug-in may not fix the issue and the only remedy is to change the registry key that was modified by the plug-in. He also stated that the Google Apps Sync plug-in modifies a registry key that is used by the Outlook Connector, which results in error message stating that ‘some functionality will be disabled’. For this, users can click ‘yes’ and the Connector will then continue to function normally.

The Google Apps Sync, which was launched last week for Microsoft Outlook, allows users to connect to Google Apps for e-mail, calendar and contacts data. It also allows users to continue using Outlook, but the back-end functionality and storage, instead of residing on the Microsoft’s internal servers, would move on to Google servers.