Why does the Mac OS X (10.6) Finder stop being able to connect to Windows computers?

Question

We have one Mac (a MacBook Pro Unibody) amongst our Windows machines which connects to the "server" (actually a Dell running Windows XP Pro) to access documents. This works just fine most of the time, but sometimes after waking from sleep, it cannot connect to any Windows computer on the network.

There are no errors (nor even any messages) in the Console application when attempting to connect either by the Finder's network browsing, nor when using the "Connect To Server" menu, either by name or IP.

I have tried "Relaunch" on Finder, toggled File Sharing, disabled and re-enabled the Airport, but nothing makes the Mac able to connect again until I reboot it!

Other computers can connect to the machines, so it is definitely the Mac at fault.

Are there any workarounds that anyone has found? Is there perhaps a way to re-start the samba client?

Edit:

The laptop is indeed using wireless, but all network connectivity is working, the Mac can ping the XP host it's trying to connect to and browse the internet just fine. I've tried using the IP address of the host machine in the "Connect to Server" menu item; That is now mentioned above.

Answer 1

[Edit: Removed questions you answered in your edit, asked new questions, made clarifications.]

1. Does the mounted SMB share (or a folder with the same name) still show up in /Volumes ?
2. What does the mount command report?
3. Does umount /Volumes/<name of share> do anything? (Note that it's "umount", not "unmount").

Note that Mac OS X's Console log generally only reports messages from apps that run as the current user. Software that runs as root (or "nobody" or any of the default restricted system accounts like "www") generally logs to /var/log/system.log or other logs. In 10.6, kernel messages, which most likely include filesystem messages, go to /var/log/kernel.log, so look there too. The Console app lets you browse all these logs if you hit "Show Log List". Mac OS X's SMB client (which I seem to recall is Apple's own implementation, not Samba-based derives from Boris Popov's FreeBSD smbfs, which is not Samba-based) probably doesn't run as the current user, so it probably doesn't log to the console log. Look in the system.log and the kernel.log.