Active AAM server freezes..???

Sounds crazy, and have been researching this problem for months.
We have 6-SQL farms and 3-File Server farms.
All farms are 2003 server SP1 (not R2).
In the last 3 months, this has happened 8 times, on 3 different farms, (2-SQL and 1-File).

The primary server freezes, hangs, inaccessible..
The server will respond to ping, but does not respond to remote requests or local KVM. The machine must be hard booted. Once it's shut down, the secondary immediately comes up and takes over AAM resources.

I can fail back and everything is fine..

No entries in any Event Logs or AAM log. The secondary only logs that the primary is not responding and a resource group shutdown request has failed.
No dump file, logging is set to high..

I have lots of info, please feel free to ask specific questions.
Has anyone else seen this?