Computer on your network that has a few network mapped drives, you may have noticed that in some cases these network mapped drives may disconnect from the network itself after certain period of time of inactivity, and that a red “X” shows up on.
Reason:
These are actually misleading because if you try to access it again it reconnects automatically and the red X disappears right after. The reason why this happens is because Windows 7 system can drop the idle conections after a specified timeout period, 15 minutes by default
Solution:
Client side: involved following registry change
HKLMSYSTEMCurrentControlSetServicelanmanworkstationparameters
If KeepConn does not exist, create it in Reg_Dword, and set the time in seconds.
Server side: Run follwing DOS command
net config server /autodisconnect:-1
Microsoft addressed this issue in following KB
http://support.microsoft.com/kb/297684