Delays when network disconnected

Whenever my laptop is disconnected from the network, there is a 5-10 second delay when launching some applications. When this happens I can see the network icon in the taskbar show activity sending (but not receiving) for the duration of the delay.

It happens all the time when running any command from a DOS prompt, and when running some other applications, but there are some applications that don’t have this problem. As soon as I reconnect to my office network the problem goes away (but there’s still a problem when connected to other networks). I’ve seen the problem on both Win2K & WinXP, and I’ve seen it on at least 1 other machine. Note that on my office network we have Netware file servers.

How can I solve this problem?