Outlook Disconnected after resume from sleep mode

Hi All,

We are having some issues with our laptop users that lock their laptops while connected to the LAN and put them into sleep mode and when they re-connect to the LAN or connect through VPN they get a message saying that their connection to Exchagne is unavailable.

When i right click on the Outlook icon and go to connection status sometimes it will say that Directory is disconnected and hitting reconnect lets them back in. Other times the connection status box will be blank and when i hit reconnect it prompts for credentials but when they put in their username/password it just keeps prompting and nothing happens.

The laptops are all running windows xp with Outlook 2007 and I've verified that I can ping the exchange servers ok when the issue occurs. The users can access Lync and all their other applications but Outlook seems to be the only one affected. They are logging onto a windows 2008 R2 domain running Exchagne 2007.

This is what I've done so far:

- Verified i can ping the exchange servers
- Disabled the "Allow the computer to turn off this device to save power" power management setting on the NIC's
- Added the RPC DefConnectOpts register key and set value to 0
- Checked the event logs on the clients and exchagne servers but all clear
- Checked for event log entries to see if MAPI connection limits were been reached but all was clear
- flushed DNS  cache and ARP caches on the client

I think the issue might relate to the fact that they lock the clients and unlock when they connect back to the LAN, but I'm all out of ideas so any help is greatly appreciated.

Thanks

AA