A California company has voluntarily recalled 100,000 portable crib-playpens, the Consumer Product Safety Commission said today. Two infants have died, and two others were injured, after the top rail on playpens sold under the brand names "Home and Roam" and "Baby Express" collapsed. The playpens, which are manufactured by Baby Trend Inc. of Pomona, Calif., can appear to be set up properly even though the top rails are not completely locked. As a result, babies can get their heads stuck in the railing and suffocate. Consumers were advised to call the company at 800-234-1879 to have their top-rail locks replaced without charge by safer new locks.