Description
This error occurs in the Quartus® II software version 4.0 when using the
always construct with a wildcard, e.g., always @ (*).
This problem is fixed beginning with version 4.1 of the Quartus II software.
To avoid the problem in versions earlier than 4.1, specify signals explicitly in the always construct's event control, e.g., always@(<signal 1> or <signal 2> or <signal 3>) instead of always@(*).