It sounds like your school has a proxy server set in IE, which is where messenger can load its proxy settings from.
Open IE and go to Tools >> internet options and select the "Connections" tab.
Then click Lan settings and uncheck the check box i circled
![[Image: attachment.php?pid=620654]](http://shoutbox.menthix.net/attachment.php?pid=620654)
Note: you will probably need to recheck the option whenever you want to use the laptop at school.