URL Hack Page Display Issue

Hey everyone,

I am having an issue with the way a page is displaying with a hacked URL.

I have a new button that overrides the old new opportunity button to prepopulate look up fields.

Here is my button:

/006/e?
CF00NF000000CFJSi={!Loan__c.Name}
&CF00NF000000CFJSi_lkid={!Loan__c.Id}
&CF00NF000000CVahZ={!Loan__c.Borrower__c}
&CF00NF000000CVahZ_lkid={!Loan__c.BorrowerId__c}
&opp4={!Loan__c.Portfolio_Owner__c}
&opp4_lkid={!Loan__c.Portfolio_OwnerId__c}&
retURL=/{!Loan__c.Id}&saveURL=/{!Loan__c.Id}

The issue I am having is with the page, it displays another salesforce inside of the existing salesforce page. If anyone has any ideas or work arounds to this that would be awesome! Thank you so much in advance.