Modifying autodisconnect for shares:

1. On the machine that is shared, open the registry (regedit.exe)
2. Go to hkey_local_machine\system\currentcontrolset\services\lanmanserver\parameters
3. double click autodisconnect
4. Set to decimal and set the number of minutes (from -1 to 4294967295, however XP will not accept a negative number)
5. Click OK
6. Close the registry editor
7. Reboot the machine