NAT Server Drops WAN IP Information with Inbound Connection

'm using Windows 2003 Server with Network Address Translation to split a
cable-internet accross a network of computers. Computer OS's range from
Windows 98 to Windows XP, and some Mac OS X.

It seems whenever somebody makes an in-bound connection, directly to the
server (via. FTP, RDP, or VNC) from outside the network, for an extended
period of time... it won't let any internet traffic though (It gets slower and
slower, until it finally drops the access). It says it still has the IP information,
but again, won't let any connections to be made.

When I go to renew the IP information, I get the message: "Unable to contact
DHCP Server"
If I tell the connection to repari, I get the message: "Repair Failed: Can't
Flush ARP Cache"

The only way's I've been able to fix this is one of the following:
(1) Unplug and re-plug in the Cable Modem
(2) Disable, then Re-Enable the NIC that teh Cable Modem is Plugged into

Does anybody have any insight to why this is happening? or how to fix it?
Does this seem like a Windows Issue? or a should I be talking to my ISP?

Any Help would be appreciated...

Thank-You

I fixed the problem myself ... turns out it was a bug in the driver with my
NIC Card (Intel Pro/1000 MT) ... an updated driver fixed everything.

>-----Original Message-----
>'m using Windows 2003 Server with Network Address Translation to split a
>cable-internet accross a network of computers. Computer OS's range from
>Windows 98 to Windows XP, and some Mac OS X.
>
>It seems whenever somebody makes an in-bound connection, directly to
the
>server (via. FTP, RDP, or VNC) from outside the network, for an extended
>period of time... it won't let any internet traffic though (It gets slower and
>slower, until it finally drops the access). It says it still has the IP
information,
>but again, won't let any connections to be made.
>
>When I go to renew the IP information, I get the message: "Unable to
contact
>DHCP Server"
>If I tell the connection to repari, I get the message: "Repair Failed: Can't
>Flush ARP Cache"
>
>The only way's I've been able to fix this is one of the following:
>(1) Unplug and re-plug in the Cable Modem
>(2) Disable, then Re-Enable the NIC that teh Cable Modem is Plugged into
>
>Does anybody have any insight to why this is happening? or how to fix it?
>Does this seem like a Windows Issue? or a should I be talking to my ISP?
>
>Any Help would be appreciated...
>
>Thank-You
>.
>