Outlook disconnected, will not reconnect

We are experiencing an issue with Outlook where it becomes disconnect (for no apparent reason) and will not reconnect.  These users are able to connect to other intranet websites and servers, as well as ping the mail server.  Their passwords have not expired and their able to use webmail.  Send/Receive action returns an error that the mail server connection is unavailable.  Both of these users/clients are on laptops with Office 2007 on Windows XP.

The first time this happened we were able to resolve the issue by restarting the mail server (not ideal).  

The second time it occurred with the same user (and same client) and cleared its self up before we could resolve the issue.  

Now it has happened on a second user/client and it has not fixed itself yet.
Neptune ITAsked:
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Are the users inside or outside of the office?
Inside the office, it may be a physical traffic or connectivity issue.  Are they hard wired or wireless?  Any desktop firewalls?  Recent Windows Updates?  Anything else changed?

If outside the network, are you using VPN, RPC over HTTP, etc?

You should check and see if  Cached Exchange Mode is enabled, which would force Outlook to only connect long enough to synchronize folders and then disconnect.  Can be tricky with spotty network connectivity.
Neptune ITAuthor Commented:
They have internal wired Ethernet connections to their docking stations.

No desktop firewalls (set by the domain policy but I double checked also).

There have been recent windows updates but many people have had the same updates with no problems.

Cached mode is set to Download full items and is enabled.
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I would look at the server first, it sounds like the issue is not limited to one machine.  Make sure of the basics first.... services are all started, run a checkdisk, make sure the resource usage is normal, etc.  
The reason I say look at the server is because that was the behavior that my stations exhibited last time my server had problems.  It was a server firewall issue in my case though.

Other than that it should be straight forward, try a different network cable on the laptops, check the switch(es) etc.

Also XP SP3 has caused network connectivity issues on HP laptops and possibly other brands as well.  Network connections disappear from Windows and connectivity is intermittent.  Might be an idea?
Neptune ITAuthor Commented:
This problem has occurred on another user's machine.  He has Office 2007 on Windows XP SP2 with all the office updates.  I checked all the things on the server and they all checked out.  We reinstalled the network drivers on this user's computer because we had read something about that being an issue on another site, but the problem cleared up after the reboot.  Now I don't know if that is because of the network driver or because of the reboot.

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Quite likely it was the drivers.  I have seen that before too.  Glad you got it fixed!
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