[support] Drupal, MySQL 5, and caching?

[codepoet at codepoetry.net]

I'm running into a bit of a problem and I'm not seeing an out.  I run  
several Drupal sites that work just fine (macgeekery.com and  
codepoetry.net among them) so I'm not new to this, but this one has  
me a bit confused.

I installed a fresh copy of 4.6.4 on a brand new Linux 2.6 server  
running:

Apache 2.0.54
PHP 5.0.5
MySQL 5.0.16

The very first page loads without issue after I turn on caching.  The  
next load of that page as an anonymous user, coming from the cache I  
would suppose, gives me a white screen with no errors in the Apache  
error log (and a 200 in the access).  In the watchdog log I get the  
famed error:

Duplicate entry 'http://triton.codepoetry.net/' for key 1 query:  
INSERT INTO cache (cid, data, created, expire, headers) VALUES  
('http://triton.codepoetry.net/', '

I searched Google and drupal.org and got a *lot* of hits ... and read  
them all.  This incarnation, however, isn't a race condition as older  
forum posts would indicate ... this is every single page hit to a  
cached page.

If I turn off caching then the site works as expected, logged in or  
anonymous.

Now, CP and MG are run from MySQL 4.1, so is it possible some SQL  
behavior changed in-between that Drupal doesn't like?  Is anyone  
using MySQL 5 with caching and no errors?

Thanks for anything you have...