Dev Balasubramanian, Outlook Product Manager, posted the heads-up on Microsoft's blog, saying that when a Google Apps user installs the sync plug-in for Outlook, the plug-in modifies a registry key which disables Windows Desktop Search from indexing and searching all Outlook data, not just the Outlook data being synchronized from GMail.

Since Outlook search relies on the indexing performed by Windows Desktop Search, Outlook search functions are broken as a result.

Balasubramanian said that uninstalling the plug-in may not fix the flaw. The only remedy is to change the registry key that was modified by the plug-in- clicking the link for more details about the registry key.

Another bug was also found that affects users of the Microsoft Office Outlook Connector which syncs Windows Live Hotmail with Outlook, Balasubramanian said.

When a user has the Outlook Connector installed, then installs the Google Apps Sync plug-in, the next time Outlook is started an error message comes up that says "some functionality will be disabled." The Google Apps Sync plug-in modifies a registry key that is used by the Outlook Connector, which results in users seeing this error message.

Balasubramanian recommends that when users see the error message they should click "yes" to enable functionality. The Outlook Connector will then continue to function normally since it will reset the registry key to the correct value.

According to Balasubramanian, Microsoft has reached out to Google, saying it will help the search engine giant come up with a long-term fix.

"We have brought these issues to Google's attention, and have offered to work with them to find a resolution for our mutual customers," Balasubramanian said. "As soon as this is done, we will publish more information."