Why does the Quartus® II software freeze when I add a signal to the SignalTap II Logic Analyzer?

Description

Due to a problem in the Quartus® II software version 12.0 SP2 and earlier, the Quartus II GUI may freeze when adding signals in the SignalTap™ II Logic Analyzer if your quartus2.qreg file contains an invalid statement.

Resolution

To work around this problem, open quartus2.qreg and remove any lines that contain the text "Node_finder". The quartus2.qreg file can be found in the following location:

• Windows 7: C:\users\<username>
• Windows XP: C:\Documents and Settings\<username>
• Linux: ~/.altera.quartus 

This problem is fixed beginning with the Quartus II software version 12.1.