new install of imp

[David Bishop]

In fact, my *first* install of imp :-)  And after having mucked around with 
postgresql, mysql, installing php, phplib, and assorted other goodies (hooray 
for apt-get!), I was to the point that imp should have worked.  However, it 
isn't :-)  As background, I'm running debian/testing, a fairly fresh install 
(about three days old, not a ton of stuff on it).  I think I followed all of 
the various readme's (that is, the database readme, the phplib readme, the 
horde readme, the imp readme, and the mysql readme), and have verified that 
my webserver works with php.  However, when I try to access imp or the 
/horde/test.php3, it returns with this error:

Fatal error: DB_Sql is already a function or class in /etc/horde/db_mysql.inc 
on line 12

Looking at line 12 of that file, it is just declaring the DB_Sql class, 
nothing special.  It doesn't seem to be declared seperately in prepend.php3 
or local.ini or php3.ini.  Searching via google and the mailing list search 
engine, all I came up with is this (unanswered) question:
http://www.google.com/search?q=cache:29eba4f595ce00e7:archives.linuxbe.org/arch033/10229.html++Fatal+error:+DB_Sql+is+already+a+function+or+class+in+/etc/horde/db_mysql.inc+on+line+12&hl=en

and http://marc.theaimsgroup.com/?l=imp&m=96466371214802&w=2 which gets a 
reply asking for further information, a reply to that, and then nothing.  So, 
where do I start?  As I'm not the only one having this problem, I can safely 
assume there are other idiots out there as well B-)  Help?  Please? 

Thanks,

D.A.Bishop