Power Steering Problem

[zaac]

I shut my truck off for 10 min when it was very cold and when I started it back up the power steering pump groaned for a second and then it blew the return line off of the steering box. I put it in a heated shop overnight and after reinstalling the hose and filling fluid i started it up and it groaned again but only for a split second and then was back to normal. I'm assuming that cause it was so cold that it froze up somewhere in the return line or cooler but why? Fluid was changed a couple of months earlier. I'm worried that it's gonna happen again next time its cold. Anyone ever have this happen to them?

[zaac]

Would a stuck pressure regulator valve cause this?

 

Also noticed the truck pulls to one side now. If the regulator stuck could the excess pressure cause an internal leak in the steering box?