Now, this is a hard one I think, at least to explain:

brief explanation: (full code later)

imap_open + imap_getmailboxes -> works fine alone

Database connection + imap_open + imap_getmailboxes -> generates this error: 

Warning: Unable to find stream pointer in /usr/local/apache/htdocs/folder/correo_carpetas.php on line 8 (where imap_getmailboxes is)
imap_getmailboxes failed: 
Warning: Unable to find stream pointer in /usr/local/apache/htdocs/folder/correo_carpetas.php on line 21 (where imap_close is)

I tried with two database connections: against MSSQL 7.0 and Oracle8i. Just a call to mssql_connect or OCIPLogon spoils the whole thing. Comment that line, and all the mailboxes will be listed fine.

Full example:

<?php

/* fails with Oracle8i + PHP (IIS/Win32 or Apache/Linux) */
/* also fails with mssql_connect under IIS/Win32 */
/* comment the next 3 lines and everything will go ok (it's just like the sample provided in PHP manual ! */

$c1 = ociplogon("myuser","mypwd","devunix");
ocilogoff($c1);

	$mbox = imap_open("{tux.comunet.es}","user","userpwd",OP_HALFOPEN) || die("can't connect: ".imap_last_error());
	 
	$list = imap_getmailboxes($mbox,"{tux.comunet.es}","*");
	if(is_array($list)) {
	  reset($list);
	  while (list($key, $val) = each($list))
	  {
	    print "($key) ";
	    print imap_utf7_decode($val->name).",";
	    print "'".$val->delimiter."',";
	    print $val->attributes."<br>\n";
	  }
	} else
	  print "imap_getmailboxes failed: ".imap_last_error()."\n";
	 
	imap_close($mbox);                        

?>

I hope I made myself clear. Ask me whatever you need.

Greetings,

F.J. Ortiz