Help with preg_match and windows domain logins...

I'm trying to do what should be a very simple regex, but can't seem to get PHP to work, yet regex-coach and even an XML .XSD work fine: Valid forms of a windows logon are: "foo\bar" "\\foo\bar" function isValidWinLogon($logon) { //$logon = '\\\\foo\\bar'; $logon = '\\foo\bar'; print "<P><PRE>logon = '$logon'<BR></PRE>\n"; preg_match('/(\\\\)?.+\\.+/', $logon, $matches); //preg_match('/(\\\\)?.+(\\).+/', $logon, $matches); print_r($matches); return (count($matches) > 0); } I'm obviously passing in the strings, but for testing, I tried to hard-code it. First, when I use single ticks, I thought that meant to be taken literally. Seems I still have to escape (\) the backslashes. In either case, the $matches array is EMPTY. Further more, WTF do I get this error: "Compilation failed: missing ) at offset 12" (pointing to the commented out preg_match. WTF should adding a set of parenthesis cause a compilation error?! # php -v PHP 5.0.3 (built: Dec 1 2005 02:20:49) Copyright (c) 1997-2004 The PHP Group Zend Engine v2.0.3, Copyright (c) 1998-2004 Zend Technologies with Zend Extension Manager v1.0.9, Copyright (c) 2003-2005, by Zend Technologies with Zend Optimizer v2.6.0, Copyright (c) 1998-2005, by Zend Technologies