Outlook 2007/2010 prompting for passwords

I had migrated exchange 2007 server to exchange 2010 with DAG,when outlook is configured in cached mode, outlook prompts for user credentials every now and then.if i remove the cache mode then its fine, this issue is for all the users.
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How are the users connecting? is this via outlook anywhere?
also when you get the prompt box, where is it trying to auth. to? it's in the top bar.
rahimpaAuthor Commented:
yes its via outlook anywhere,  yes its in the top bar
no i mean is the correct hostname in the top bar?
also how do you authenticate?
basic or ntlm?

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