We often meet this issue error.
It is caused by Projeqtor or the System environment (Windows server / Apache / PHP..) in your opinion ?

PHP Warning: PHP Startup: in Unknown on line 0
[Wed Dec 17 16:13:55.726928 2014] [mpm_winnt:notice] [pid 5468:tid 296] AH00354: Child: Starting 150 worker threads.
[Wed Dec 17 16:13:57.903955 2014] [:error] [pid 5468:tid 1704] [client 192.168.1.60:51970] PHP Fatal error: Call to a member function query() on a non-object in C:\wamp\www\projeqtor\model\persistence\Sql.php on line 66, referer: http://192.168.1.12/projeqtor/view/main.php
[Wed Dec 17 16:13:57.903955 2014] [:error] [pid 5468:tid 1704] [client 192.168.1.60:51970] PHP Stack trace:, referer: http://192.168.1.12/projeqtor/view/main.php
[Wed Dec 17 16:13:57.903955 2014] [:error] [pid 5468:tid 1704] [client 192.168.1.60:51970] PHP 1. {main}() C:\wamp\www\projeqtor\tool\checkAlertToDisplay.php:0, referer: http://192.168.1.12/projeqtor/view/main.php
[Wed Dec 17 16:13:57.903955 2014] [:error] [pid 5468:tid 1704] [client 192.168.1.60:51970] PHP 2. require_once() C:\wamp\www\projeqtor\tool\checkAlertToDisplay.php:4, referer: http://192.168.1.12/projeqtor/view/main.php
[Wed Dec 17 16:13:57.903955 2014] [:error] [pid 5468:tid 1704] [client 192.168.1.60:51970] PHP 3. Audit::updateAudit() C:\wamp\www\projeqtor\tool\projeqtor.php:188, referer: http://192.168.1.12/projeqtor/view/main.php
[Wed Dec 17 16:13:57.903955 2014] [:error] [pid 5468:tid 1704] [client 192.168.1.60:51970] PHP 4. SqlElement::getSingleSqlElementFromCriteria() C:\wamp\www\projeqtor\model\Audit.php:103, referer: http://192.168.1.12/projeqtor/view/main.php
[Wed Dec 17 16:13:57.903955 2014] [:error] [pid 5468:tid 1704] [client 192.168.1.60:51970] PHP 5. SqlElement->getSqlElementsFromCriteria() C:\wamp\www\projeqtor\model\persistence\SqlElement.php:1586, referer: http://192.168.1.12/projeqtor/view/main.php
[Wed Dec 17 16:13:57.903955 2014] [:error] [pid 5468:tid 1704] [client 192.168.1.60:51970] PHP 6. SqlElement->getDataType() C:\wamp\www\projeqtor\model\persistence\SqlElement.php:1412, referer: http://192.168.1.12/projeqtor/view/main.php
[Wed Dec 17 16:13:57.903955 2014] [:error] [pid 5468:tid 1704] [client 192.168.1.60:51970] PHP 7. SqlElement::getFormatList() C:\wamp\www\projeqtor\model\persistence\SqlElement.php:1875, referer: http://192.168.1.12/projeqtor/view/main.php
[Wed Dec 17 16:13:57.903955 2014] [:error] [pid 5468:tid 1704] [client 192.168.1.60:51970] PHP 8. Sql::query() C:\wamp\www\projeqtor\model\persistence\SqlElement.php:2107, referer: http://192.168.1.12/projeqtor/view/main.php
[Wed Dec 17 16:13:58.857122 2014] [:error] [pid 5468:tid 1712] [client 192.168.1.52:57564] PHP Fatal error: Call to a member function query() on a non-object in C:\wamp\www\projeqtor\model\persistence\Sql.php on line 66, referer: http://192.168.1.12/projeqtor/view/main.php
[Wed Dec 17 16:13:58.857122 2014] [:error] [pid 5468:tid 1712] [client 192.168.1.52:57564] PHP Stack trace:, referer: http://192.168.1.12/projeqtor/view/main.php
[Wed Dec 17 16:13:58.857122 2014] [:error] [pid 5468:tid 1712] [client 192.168.1.52:57564] PHP 1. {main}() C:\wamp\www\projeqtor\tool\checkAlertToDisplay.php:0, referer: http://192.168.1.12/projeqtor/view/main.php
[Wed Dec 17 16:13:58.857122 2014] [:error] [pid 5468:tid 1712] [client 192.168.1.52:57564] PHP 2. require_once() C:\wamp\www\projeqtor\tool\checkAlertToDisplay.php:4, referer: http://192.168.1.12/projeqtor/view/main.php
[Wed Dec 17 16:13:58.857122 2014] [:error] [pid 5468:tid 1712] [client 192.168.1.52:57564] PHP 3. Parameter::getGlobalParameter() C:\wamp\www\projeqtor\tool\projeqtor.php:57, referer: http://192.168.1.12/projeqtor/view/main.php
[Wed Dec 17 16:13:58.857122 2014] [:error] [pid 5468:tid 1712] [client 192.168.1.52:57564] PHP 4. SqlElement->getSqlElementsFromCriteria() C:\wamp\www\projeqtor\model\Parameter.php:559, referer: http://192.168.1.12/projeqtor/view/main.php
[Wed Dec 17 16:13:58.857122 2014] [:error] [pid 5468:tid 1712] [client 192.168.1.52:57564] PHP 5. Sql::query() C:\wamp\www\projeqtor\model\persistence\SqlElement.php:1445, referer: http://192.168.1.12/projeqtor/view/main.php

Thanks for your opinion.