Some versions of Opera Mini .vxp are "signed" for specific SIM cards or regions. If an app won't open, it might require a VXP Patcher or a specific launcher. If you'd like, I can help you:
Released around mid-2011, version 6.1.0 was a significant refinement over the original Opera Mini 6 "Next" generation. Opera Mini 6.1.0 Vxp -
This version is particularly remembered for: Some versions of Opera Mini