Prompting of Exchange Password frequently in outlook 2007

Few users in my company getting password prompt for exchange almost 1 or 2 times a day. After keying the password the prompt goes off but came back again after a while.
We are on pure (outlook & exchange) 2007 environment.
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B HCommented:
you should check for and run all the exchange 2007 service packs and hotfixes.

these are not offered by microsoft update, you gotta get them yourself

exchange 2007 sp2:
read the release notes, there's a side-program "installation tool" you have to run if its server 2008

after that's installed, get this:
update rollup 2 for exchange 2007 sp2

what you're seeing was actually fixed in sp1 rollup 9, but it's best to get these as they fix a lot of other stuff

afterwards, if 2008, you'll need to disable https on IIS, then re-enable it - details in the release notes

how are the clients connected to the exchange server?
directy ot RPC over HTTP?
Glen KnightCommented:
There are a few reasons why this might happen.
If you don't have Rollup 9 for Exchange installed then download Service Pack 2 and install that.

There was also a recent security update that caused a kernel authentication issue.

Try option 1 and 3 in my article here:

if you find my article useful please vote for it :)
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sovereignpakiAuthor Commented:
My all exchange server are on SP2 with Rollup 1 Installed. I can proceed for Rollup 2 but just looking for alternative solution as it's happening for apprx 4 users out of 970 users.
fyi, The console version is and using shell command version 8.2 (build 176.2)

The client are connected RPC over HTTP.
sovereignpakiAuthor Commented:
Hi Glen,
Indeed it was great article (specially to the point) and looks sensible, and I press Yes button.

I've 2x Hus/CAS (load balanced) server and in both the option "Enable kernel-mode authentication" is not checked, which I'll do after completing internal process. Fyi in both hub/cas IIS has following setting.

Basic Authentication:Enabled
Windows Authentication:Enabled
The rest are disabled.
Basic Authentication:Enabled
Windows Authentication:Enabled
The rest are disabled.
Basic Authentication:Enabled
Windows Authentication:Disabled - is this setting correct.
The rest are disabled.
Anonymous Authentication:Enabled
Basic Authentication:Enabled
Windows Authentication:Enabled
The rest are disabled.

sovereignpakiAuthor Commented:
Hi, I've enabled the kernel-mode authentication but still user getting password prompt.
under RPC virtual directoy the windows authentication is set to disabled, is this correct setting or should i enable it and set kernel-mode authentication for rpc VD as well.
I've asked field support to change to Basic Authentication if it is set to NTLM, could it cause this issue.
sovereignpakiAuthor Commented:
outlook authentication changed from NTLM to basic authentication on outlook "proxy authentication setting".
waiting for user confirmation.

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