CRJ with a single pack deferred departed only to have a pressurization problem climbing through 16;000 FT.

Narrative

While climbing through 15-16;000 FT I noticed the cabin altitude pressure was much higher than normal and climbing. We told ATC that we needed to level off; so we stopped at 17;000 FT and the cabin altitude continued to climb and we then started a descent. We received a caution message that our cabin altitude exceeded 8500 FT and we ran our QRH procedure for that alert while still requesting a lower altitude. Then we receive a warning message that our altitude exceeded 10;000 FT and we ran the QRH procedure for that and leveled off at 10;000 FT MSL (safe altitude). Continued to our destination without further incident. No sure what caused the problem; but we were already flying with our left pack deferred; so by elimination of that pack; I would guess that the problem originated from the right pack and an associated valve since we weren't pressurizing properly; but cannot be sure since we really didn't have time to analyze the situation beyond what was involved in following our checklist procedure.