In a Microsoft Exchange Server 2007 environment, the week numbers that are displayed in the Outlook Web Access (OWA) calendar do not match the week numbers that are displayed in the Microsoft Office Outlook calendar. This issue occurs when you use the English or French version of OWA and of Outlook. For example, in the English version of OWA, the first week number is 2 instead of 1 for the year 2010. However, it is different when you use the English version of Outlook.
To resolve this issue, install the following update rollup:
2608656 Description of Update Rollup 6 for Exchange Server 2007 Service Pack 3
After you install this update rollup, Exchange Server 2007 OWA provides an option to select when the week numbers start.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
For more information about the client features in Exchange Server 2007 OWA, visit the following Microsoft website: