This might be a funny little problem with autodisconnect that I've seen from time to time in WinNT, Win2K, but not yet in WinXP. I just checked in my registry, and I see that same entry with the same default setting (15) that has caused the occasional user a problem. There are a lot of reasons why some machines do, and others don't, just automatically re-establish the connection when it's required again. I've suspected that the power management features of some NICs are such that they don't recover well from a disconnect in one OS or another, but also there are security settings which would affect the ability to reconnect.
If you look at
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\LanmanServer\Parameters
for a REG_DWORD named "autodisconnect" you'll probably see that it has a hex value of "f" ("15" decimal). If you set it to "-1", that should prevent autodisconnect from occurring. That atleast should help you learn whether or not this is actually your problem. To tell you the truth, I'm not certain whether or not this should require a reboot to become effective. I think not, but it couldn't hurt to do it anyway.
There is another way to accomplish setting of autodisconnect from the CMD prompt, but it has other ramifications. It used to disable system autotuning in NT4 and Win2K. I'm not sure about WinXP, but I wouldn't risk it. Just for the record, though, the command is
net config server /autodisconnect
with the time interval desired entered immediately after autodisconnect (with no space intervening). In NT4 this would cause the registry value to be set to the upper limit, rather than to -1. Weird, huh? Effectively the same for the purpose of this one parameter since the time span would be quite long. But, like I said, this really isn't the best way to do this.
The registry is your best bet -- IF this is actually your problem. Can't hurt to give it a try. You can always change the setting back later if you decide that your issues are caused by something else.
- Collin
Just an additional note: The reason I mention power management features in NICs is that some power management features in at least some NICs are enabled regardless of the OS power management settings. Some have power management features that are controllable through driver utilities, and some are just on all the time regardless of what you do. I've especially seen this in PC Card NICS and some of the mini-card NICs found in notebook computers.