Is autodisconnect turned off See:-http://support.microsoft.com/default.aspx?scid=kb;en-us;297684&Product=win2000
And make sure the laptop don't have powersaving enabled or going into suspend mode, especially the machine where the data resides.

>>Are the laptops hard wired or using wireless access to the network,if the later get the client to get rid of the wireless.
>>
>
>They are hard-wired. No wireless involved.