The certificate was not installed. Please try again. Outlook 2010, Exchange 2007, Windows XP Pro SP3 client

I've been asked by my customer to resolve an issue with being asked for a certificate every time they log on to their Outlook.  It mentions the certificate twice.  I have taken the certificate from the Public Downloads directory on the server and attempted install with the InstallCertificate file.  I get The certificate was not installed message.  

Any ideas of what I can do to rid this system of this error.  It happens each time they open their Outlook.  If they click yes twice, it connects.  I'd like the message to go away all together.
Who is Participating?

[Product update] Infrastructure Analysis Tool is now available with Business Accounts.Learn More

I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

You can try installing the certificate by itself.  Just open the file, and select "Install...", then instead of automatically selecting the location, Browse the stores, check the box for "Show Physical Stores", and under Trusted Root Certificate Authorities, put the cert in Local Computer.  Then try browsing the site through OWA, and see if you get a certificate error.  

Is this a SAN cert?
First of all, how long have they been receiving the certificate error? Are they connecting inside or outside of the network?

You need to purchase an SSL certificate for Exchange (preferrably a UCC) that includes your domain, your exchange server/netbios and your external fqdn for your exchange server. If you need assistance installing or verifying whether or not you've installed it properly, please follow the below link for step-by-step instructions. GL!

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Windows Server 2008

From novice to tech pro — start learning today.