Exchange 2007 - Outlook clients get a constant credentials popup

The domain is setup on a Server 2000 box.
Exchange is setup on a SBS 2008 with Exchange 2007.

The outlooks clients collect to ExchangeServerName.workgroup.local
The clients get a constant username/password prompt while in outlook.

I don't know what my next step should be.
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Shreedhar EtteCommented:

Does Exchange 2007 has been updated with the Service Pack 2? If not then update it first.

Also refer this article which covers the most common causes:

Hope this helps,

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nicaldanAuthor Commented:
SP2 did it - thanks!
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