how to detect moment when mapped network drives are lost on Windows 7

For some reason, I keep losing access to my company's network drives. I'm using Windows 7. What could cause this? I'm the only one that VPN's to a certain client using the Windows 7 VPN functionality, but I haven't confirmed this. Is there something I could implement that tells me the moment that I lose access, so I can easily determine the cause (perhaps with a windows service)? This isn't my question, but I'll give extra bonus points if you can tell me the cause. :-)

Error Message if VPN'ed too long:

I always have to fix them by doing the following:

net use u: /delete
net use u: \\company.local\dfsroot\users\myusername

Screen Shots for VPN setup:

You're losing them completely, or they are temporarily disconnected? Win7 I believe has a timeout that will disconnect unused shares (puts an X on My Computer) but reconnects when you try to use the share again.

If you're mapping over the VPN, it could be that your VPN isn't forwarding certain packets needed to keep the connection alive, or it could be a configuration issue depending on how you're doing it (such as suggested off http://social.technet.microsoft.com/Forums/en-US/smallbusinessserver/thread/22358ba5-eba3-4a34-a935-bb18a92a8dbe )

You might want to elaborate more on how you're configured; we know the client is Win7, but what is the server running, and what kind of VPN configuration do you have? And is the issue permanent, or does your fix still fail after awhile? Is there anything in the logs? How is your connectivity to the server? Is the connection reliable? Are there logs on the VPN server? Information on these items can help narrow down the issue.