emergency!!how to solve tihs internal error?

Is there a specific reason you need to run Quartus II 6.0?

My recommendation delete the db directory created in the synthesis directory, then re-run the compile. This often help's with weird errors.

The next possibility is to upgrade to Quartus II 11.1sp1. (If you are using a current family still supported in the webpack)

If you have an old Cyclone or earlier part, you may need to download the latest webpack that still supports that version. (I know they dropped several of the legacy devices around 10.1 or so)

Pete