This problem has me stumped :

I have a WinXP Home machine with a Realtek NIC, a Mandrake Linux 9.1 machine with a Netgear NIC, a Smoothwall Linux Firewall machine with two 3Com SOHO100TX NIC, an iBook running Mandrake Linux 9.1 with a Airport card, and a WinXP Pro Laptop with a Dell True Mobile Wirless NIC and a 3Com wired NIC all on a Linksys Wireless Router with 4 port switch. The Router is running as a Hub and the Smoothwall Firewall is the Router/Firewall from the internet. All internet activity on all machines works fine with no problems. The Laptops can share files with the WinXP Home machine with no problem. The problem is when any computer tries to transfer files to/from the Mandrake Linux desktop. I have setup Samba and all permissions are set and can successfully transfer small files back and forth, but when I am transferring large files (i.e 700 MB and up) I will get "The specified Network is unavailable" error and the transfer will hang. If I reboot the Linux and which ever computer was trying to transfer I can start transferring again with no problem, but it will timeout again.

Any Ideas?