>I have a VFP8 app (which I can recompile for VFP9 if necessary) running on 4 Windows XP Pro SP2 PC's. All PC's are opening a DBF on the Windows 2003 server via a mapped drive Z: network share. To eliminate any DHCP lease timeout issues, all PC's (and server) are assigned static IP addresses (10.0.0.x) on the LAN. The 2 PC's connected right next to the Windows 2003 Server on the same switch never get an error. However, the 2 PC's that are in distant parts of the building connected via a VLAN get a mapped drive Z: does not exist error every so often. I tried changing the autodisconnect registry key on those PC's thinking it was the 15 minute autodisconnect "feature", but this had no effect. When I look in My Computer, drive Z: is there, with no red X on it. If I click on drive Z:, it takes perhaps 5 seconds to pull up the folders on the server, and all is well again. If there was a way to lengthen the timeout of my USE statement, to perhaps 10 seconds, I think this error would go away. Seems like VFP gives up a little too quickly.
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>I've tried running a ping -t 10.0.0.10 in a minimized DOS box to keep the TCP connection alive to the server, but this has no effect.
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>I've tried running a minimized VFP app that does a DIR Z:\ every 30 seconds to keep alive, but this has no effect.

Machines on your VLAN are having problems, locally connected ones do not. I'd take a hard look at the configuration of the VLAN. You've told us nothing about it, but they can be complex and its management software may be capable of timing out connections if configured incorrectly (for VFP, anyways). For example, maybe your VLAN is configured to auto-disconnect "inactive" connections if there's a slow link somewhere between those distant machines and your server, to prevent saturation of that link. Another thing to be wary of is if there's any sort of proxy, caching or otherwise, in the "VLAN", and/or if there is any software required on the distant computers to work properly with the VLAN (i.e. unusual network protocol).

It may be that the network admin is not aware how demanding VFP is. If you need to discuss this with him/her, there are some general talking points in message#1328061 .

BTW for lurkers, on a vanilla Microsoft network where the W2K3 server is the DHCP server, you never have to worry about DHCP lease expirations. There are some valid reasons for using static IPs (the server should have one), but if you are or were having problems with lease expirations you've got a DHCP server or client misconfiguration, or some other sort of network problem. For everyday workstations, DHCP makes management a lot easier. If you moved to static IPs to try to address this missing drive Z: issue you're probably trying to treat a symptom rather than the root cause.

If you still want to implement a keepalive as a workaround, maybe you could create a dummy folder and table on Z: and USE that SHARED from time to time, plus maybe a SELECT, rather than just a DIR Z:. This exercises more network layers than just a folder enumeration and might be more effective.