Random open_basedir -effection?

Folks, I've noticed that I got "open_basedir restriction in effect" warnings randomly in a random situations. I've seen this error appearing whether the script is using filesystem or not. And the weirdest thing: I don't have any open_basedir restrictions set! Just a second ago I got following error from PHP: Warning: open_basedir restriction in effect. File is in wrong directory in Unknown on line 0 Warning: Failed opening '/var/www/ank_myynti/www/ajoneuvot/index.php' for inclusion (include_path='.:/usr/local/lib/php') in Unknown on line 0 a) I'm not trying to include that index.php mentioned above, I try to open it! b) The index.php script is not using filesystem at all This effect is very rare but it happens sometimes anyway. And as I said without any frequency but completely randomly. My PHP is 4.2.3 ruinning as a Apache module for 1.3.26 in Linux RH7.3. Thanks, Ville