An Internal Error while using quartus II 9.0 ,waiting for help

[Altera_Forum]

Internal Error: Sub-system:AMERGE,File:/quartus/atm/amerge/amerge_kpt_op.cpp,Line:390 

kpt_mgr->save_keypoints_db(map_kpt_db->get_name(),map_save_file_name) Stack Trace: 0x3E2AF: amerge_mini_merge+0x3AECF(atm_merge) End-trace Quartus II Version 9.0 Build 132 02/25/2009 SJ Full Version  I've met this problem, and don't know how to solve it. If you know why, will you give me the resolusion or some advice? Many thanks!

[Altera_Forum]

1. you can try deleting db and incremental_db in the project directory 

2. if that doesn't work you should update to a newer Quartus II

[Altera_Forum]

So many thanks PanCake! Deleting the db and incremental db worked for me!  

 Rgds Balu