VPN 'forgetting' local mapped drives & printer

Since late January, I've been having problems with "Program Not Responding" (primarly with MS Office applications). I didn't have the problem before that, so, I think this occured because of a change that came with an update around that time. It turns out to be due to the apps not being able to 'see' the drives I have mapped from another system on my local network, or the printer I have shared off that system.

The reason the apps can't 'see' these attached devices seems to be that VPN is 'forgetting' the connection. I am in a remote office and need to use VPN all day. I've found that when I first start my system in the morning, before starting VPN, the system and apps can 'see' these devices just fine, and, as long as I've accessed them before starting VPN, they continue to be 'visible' to for awhile. However, after a couple hours on VPN, they seem to have been 'forgotten' and the apps will start having the "Program Not Responding" problem. If I close the apps, disconnect VPN, access the mapped drives and "connect" the printer then restart VPN and the apps, everything works fine for another couple hours.

Can anyone help me resolve the issue of VPN 'forgetting' the locally attached devices? As I say, this wasn't happening prior to late January.

Thanks

PS: I'm running W7 Enterprise 64bit and the other system on my local net is XP Pro.

I found the following in one of the "Similar" threads the forum attached to my earlier post.

To turn off the autodisconnect feature, open an ADMIN command prompt, type the following line, and then press ENTER:
net config server /autodisconnect:-1

This seems like it could be the solution - I'm giving it a try and wait awhile to see if I still have the PNR problem with Office, then I'll post back either way.