I don't use [ifx_pconnect] function in my scripts.
Does this happen with the latest CVS snapshot from http://snaps.php.net/ ?
I am using PHP Version 4.0.6 and Apache 1.3.19 with Informix Dynamic Server Version 7.31.UD1 on Red Hat Linux and the error occurs eventually.
We are using PHP 4.2.1 with Redhat 9 and we get this pesky error randomly.  It will come and stay for about 20 seconds after that you can refresh and the error is gone.