During the flushing process, did you ever let the resevoir get real low? (You may have introduced an air bubble into the system.) Personally, I prefer the two-man method of openning and closing the bleeder valves. If the tubing you are using for draining doesn't fit the bleeder valve real tight, you may be sucking air back into the caliper(s).

I don't know if it applies to your model Volvo, but I believe some of them are bled in the order of: left rear, right rear, right front, left front.