When switching to the Schema page of the connection properites dialog box it is resized vertically to take up the whole screen. This only occurs when the "Cache Location" field has a value - I suspect it is due to this value being longer than the horizontal space allows (forcing it to wrap), e.g. "C:\Documents and Settings\Martin\.ldapstudio\.metadata\.plugins\org.apache.directory.ldapstudio.browser.core\schema-localhost-redir-admin2.ldif".
This also occurs on the LDAP -> Text Formats page of the main preferences dialog box.
It is a bit ugly but does not interfere with the functionality.