Null pointer error when quote page called from salesforce

Hello,

We're calling Oracle create quote page from salesforce page using the following URL/form action :

<form id="theForm" method="POST" action="https://relpre.xxx.com/OA_HTML/qotSZzdContainer.jsp">

<input type="hidden" name="qotFrmDspFile" value="qotSCocCreate.jsp" />

.

.

<input type="submit" value="Submit">

   </form>

This results in redirection to Login page as there's no session.

When redirected back to create quote page, we're losing all those form parameters sent via POST.

This is causing Null pointer exception.

But if we retry the navigation from salesforce page, as the session is created already, all the parameters are retained (no redirection to login) and quote page works fine.