Outlook 2007 can't connect to Exchange - "name cannot be resolved"

A computer running Outlook was working okay and stopped working. OWA for this user works okay.

When I fire up Outlook, I get the message:
The connection to Microsoft Exchange is unavailable. Outlook must be online or connected to complete this action.

Then, a dialog pops up to 'Check Name'. If I click Check Name, it says:

The name cannot be resolved. The connection to Microsoft Exchange is unavailable. Outlook must be online or connected to complete this action.

If I click Cancel a couple times to exit, it says
Cannot open your default e-mail folders. The file c:\documents and settings\Administrator\Local Settings\Application Data\Microsoft\Outlook\outlook2.ost is not an offline folder file.

Then Outlook closes.

I can ping the exchange server okay, I tried setting the DNS to our internal server on the local PC without success. I've read quite a few threads here, but nothing quite seems to be helping.

Who is Participating?
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.

Andrej PirmanCommented:
Open IE and check under menu FILE --> if you maybe have "Work Offline" checked. Uncheck and try again.
Andrej PirmanCommented:
I mean, the same function under FILE menu in Outlook :)
Alan HardistyCo-OwnerCommented:
Sounds like an SSL issue.  Has your certificate expired / been renewed recently?

Is it a self-issued certificate or the one installed with Exchange 2007 which expires after 1 year?

If the certificate has expired and is self-issued or is the self-generated Exchange certificate, then you will have to renew the cert and then install it on the client again to get the client working again.

Best bet IMHO is to buy a 3rd party trusted SSL cert from somewhere like GoDaddy.
Determine the Perfect Price for Your IT Services

Do you wonder if your IT business is truly profitable or if you should raise your prices? Learn how to calculate your overhead burden with our free interactive tool and use it to determine the right price for your IT services. Download your free eBook now!

Neil RussellTechnical Development LeadCommented:
It could also be just a corrupt profile.
Start by just deleting c:\documents and settings\Administrator\Local Settings\Application Data\Microsoft\Outlook\outlook2.ost and starting outlook.  If that fails, delete the outlook profile completely from control panel-> Mail and create a new one.
Neil RussellTechnical Development LeadCommented:
Have you checked the event logs for any errors occuring? This can also be caused by a pc that has lost its domain password sometimes.
silentreproachAuthor Commented:
Labsy: I can't get into Outlook at all because of the message: "The connection to Microsoft Exchange is unavailable. Outlook must be online or connected to complete this action".

Alanhardisty: How do I find out if my certificate has expired? Exchange is on a fairly recently installed SBS2K8, so I don't think this is the problem.

Neilsr: I tried deleting the .ost file, no luck. I'm checking the event viewer and I see an error under applications "Windows cannot determine the user or computer name. (The RPC protocol sequence is not supported). Group Policy processing aborted.

Is it possible that it's a group policy or firewall issue? The firewall is 'ON' and can't be turned off as it is controlled by group policy.

Neil RussellTechnical Development LeadCommented:
Firewall is a possibility yes.  But it looks more like the machine may need to be removed from the domain and rejoined with the symptoms you have and the errors in your event log.

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
Andrej PirmanCommented:
Did you try my suggestion in IE about checking and switching off Working Offline?
Just to confirm.
Andrej PirmanCommented:
Also, are you sure that you are logged-in with DOMAIN user?
Just to confirm, that you are in some case NOT logged into PC locally...
silentreproachAuthor Commented:
Neilsr: You may be on the right track. On the WinXP client machine, I went into Control Panel, System, and removed the user from the domain. Then rebooted. When I tried to re-add the user into the domain, I got the error:

The following error occurred attempting to join the domain "mydomain.local": the RPC protocol sequence is not supported.

So, I searched the knowledge base and found this article

I tried the solution in that article:
   netsh winsock reset
   netsh int ip reset c:\resetlog.txt
  Followed by a reboot

Now I can't VNC back into the machine. I might be in a bit of a pickle.
silentreproachAuthor Commented:
I decided to award NeilSr with the points, because he recommended I remove the client computer from the domain and re-join. While this did not solve my problem, I believe it helped me find the root of the problem (RPC protocol sequence not supported).

For others who follow this path in the future, this is what I did, step by step:

On the WinXP machine I went into Control Panel, System, Computer Name tab, clicked on Change and changed the "Member of" from Domain to Workgroup (I named it WORKGROUP). Then rebooted and attempted to re-join the domain through the same steps.
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

From novice to tech pro — start learning today.