Cisco ASA 5505 Firewall Bug - Resolved?

Multiple Cisco ASA firewalls, all running the same code have been exhibiting a loss of connectivity to the outside world problem:
Hardware:   ASA5505, 256 MB RAM, CPU Geode 500 MHz
Software:   asa724-k8.bin

The devices would randomly enter a state where external NIC is unable to process packets. Console
port access would work if out of band access is present; I could login and run commands. All show commands work, sometimes the device will come back w/o a reboot, sometimes a reboot is
needed to restore the proper functionality.

I one case I was able to show that:
external router cannot see layer 2 mac address (i.e. arp for) the asa
The asa CAN SEE mac address (arp) of router

My hunch is that this is a bug in the asa code and the ethernet transmitter
on the asa external interface is going to sleep.

The switch port (cisco 2950 in one case, cisco 2960 in another, both new or
less than 6 months old ...) showed up/up.

So this was not a negotiation issue, or a duplex issue.

Had remote syslog turned on in the logs at the time of a lock up and nothing
was noted in the logs besides normal connection setup tear down. No error
msg, warning, etc.

UPDATE:

Version 8 of the ASA runs a linux kernel and the cisco asa firewall code inside
a vm context within this linux kernel. You can see the kernel processes by doing a show kernel process on the cli.

This new code does not seem to have the bug, so far.