I've noticed that sometimes PHP mangles links when transparently adding the session ID to the URL.  It seems to insert the session ID into the middle of the URL.

For instance:
<a href="arraytechreport.php">
is turned into:
<a href="arraytechrepoPHPSESSID=XXXrt.php">

I saw this mentioned in a closed bug report for an old version of PHP that said it was now fixed, but I'm running 4.0.1pl2.

Configure options:
--with-mysql --with-sybase-ct=/opt/sybase --with-apxs=/usr/local/apache/bin/apxs --enable-trans-sid

I'm using the stock php.ini-optimized -- the only thing I've changed in it is I turned on register_globals.