Secondary Start Pages fail to launch at IE startup

I am setting the IE start page via the following regwrite statement in a login script:
WshShell.RegWrite "HKCU\SOFTWARE\Policies\Microsoft\Internet Explorer\Main\Start Page", "http://www.cointranet.net"
This is working as expected, however I also want users to be able to manually set additional start pages when using IE7 and IE8. Users open the additional webpages that they want to have in additional tabs and then click "Use current" in Tools > Internet Options, which successfully populates the Home page box, then click OK. This populates the HKCU\SOFTWARE\Policies\Microsoft\Internet Explorer\Main\Secondary Start Pages registry value. However when they next open IE, only the start page tab launches and the Home page box in Tools > Internet Options contains http://www.cointranet.net, but none of the secondary start pages they set. The Secondary Start Pages registry key is still populated, and if the user clicks on the Home icon in the toolbar the secondary start pages all launch. Is there another registry key or value that I need to populate/change in order for the secondary start pages to launch at IE startup and appear in the Home page box?