I have owned two P-22's, one in particular with many thousands of rounds thru it. Both have been very reliable. Like GB said, a good cleaning (.22's are a lot dirtier, and ammo sensitive the most centerfires), and testing with another magazine are in order.
Though not experiencing the issue myself, I have heard that some p-22's are very ammo sensitive. I would pick up a half dozen different makes of ammo, and try them all, until a reliable brand has been identified. If it still is not reliable, then yep, back to the manufacturer..
I like the light weight, compact size, adjustable sights, and decent accuracy of this gun, and often carry it in my back pocket for walks in the woods.
Larry