Hi, I'm having problems regularly reproducing this, so please bear with me.  
Ok, the first reason I noticed this problem in the first place was that 
whenever I reloaded the root page off of my site, about 2/3 of the time it 
would produce a 416 error.  Reloading always gives the normal page back, but 
reloading again gives the 416 error back most of the time.  Turning off 
XBitHack in my config made this behavior go away.

Ok, here's where it started to get bizarre.  I was going to submit this report 
earlier today, but in testing it with netscape on a Solaris box, it wouldn't 
show itself.  Then I tried with IE for Solaris, and it "occasionally" showed 
itself.  Then... Then I removed the user x bit from index.html, and the 
problem went away.  Then I turned XBitHack back on, and the x bit on 
index.html, and everything was -still- behaving correctly.  (?)

Here's more of the weirdness.  The whole time, if I go to index.html directly, 
ie:
http://www.vorpalcloud.org:81/index.html
instead of
http://www.vorpalcloud.org:81/
it would also work fine, XBitHack or not.  (Note that port 80 is my 
current 'production' apache 1.3.X server)

Anyway, I still can't get the 416 error to resurface itself.  However, the 
server side includes on the index.html page are not working if you don't go 
directly to index.html.  I'm not sure why it's not working with a 
DirectoryIndex style access to index.html, but it isn't.  So...  on a related 
note (why I'm including it with this bug report)....

When I go to http://www.vorpalcloud.org:81/gallery/ from IE under windows, it 
gives me the index.php script as is (doesn't actually run it), but if I go 
directly to it, it works just fine.  Likewise, from other browsers, it works 
just fine without going directly to index.php.

I don't know, something weird seems to be happening with DirectoryIndex style 
accesses.  It's like it's handing me the pages just fine, but if it's not 
bothering to procss them at all.