Redirect after PayPal

I configured my cart and PayPal account accordingly to the wiki. However, when I ran a purchase through, it returned me to http://<MYDOMAIN>/index.php?main_page=checkout_process with a whole bunch more of variables appended to the url. When I got pointed back to that URL, it was a white page with a login box on it.

Anyone know why it didn't return properly?

The order went through on the backend. When I refunded it showed refunded and all.

I have setup my cart and PayPal as per the wiki. However, when PayPal redirects back to my site, it brings the user to a login prompt. I have attached a screenshot to show.

The url that it was directed to was: http://<TESTDOMAIN>/index.php?main_page=checkout_process&referer=paypal&tx=2TT277707G102882D&st=Completed&amt=0.01&cc=USD&cm=zenid%3dntig0o933ub41okd7uph71dif6&item_number=Store%20Receipt&sig=Cdrq%2fu4evuYp7QvscAskqmjiMCYRAvF4Ih9haVNvPKByXST1QBzBSeiO1NmIU%2ffSwC8Yjlg9C88VpGw51CRTmHdprQILFwuvrrf%2fX%2f4uQ32P1Bjx0doZ4LYaeoDALY9q4bzK2Qm2JDhAftnKeucXq5sN%2fpZE4VDwB%2bWR5Ky0TRQ%3d

That's not normal. In fact, it doesn't look familiar at all.

Have you tried using Express Checkout instead?