The latest v1.51 software update fixes the symptoms which affects the game progress, mentioned as "NEXT Dynasty Warriors".
System software version 1.51 for PlayStation Vita Update
From 27 December 2011 and began updating the system software version 1.51.
To become available and some features of the PlayStation Network features, updates the system software of PS Vita (Update) is required. PS Vita also system software, by updating, adding and security can be enhanced many features. Please use the update to the latest version.
Standard software while playing PlayStation ® Vita Some symptoms have been identified that affect the game progress.
We've improved the symptoms of this software in the system.
- "NEXT Dynasty Warriors"
Source:- PS Vita (translated)