Existing users, 
Happened on two different Mac OS X 10.3.9 machines.
Here's the beginnings of the crash report (I will send the developer the entire crash report.)
------------
Date/Time: 2006-06-11 17:44:52 -0700
OS Version: 10.3.9 (Build 7W98)
Report Version: 2
Command: Aquallegro
Path: /Users/johnmill/Desktop/Aquallegro ƒ/Aquallegro.app/Contents/MacOS/Aquallegro
Version: 4.1 (4.1)
PID: 562
Thread: 0
Exception: EXC_BREAKPOINT (0x0006)
Code[0]: 0x00000001
Code[1]: 0x90a8d2c0
Thread 0 Crashed:
0 com.apple.Foundation 0x90a8d2c0 _NSRaiseError + 0xf8
1 com.apple.Foundation 0x90a8d1a4 +[NSException raise:format:] + 0x2c
2 com.apple.Foundation 0x90a2816c _decodeObjectBinary + 0x684
3 com.apple.Foundation 0x90a3f0bc -[NSKeyedUnarchiver _decodeArrayOfObjectsForKey:] + 0x29c
4 com.apple.Foundation 0x90a36980 -[NSArray initWithCoder:] + 0x170
5 com.apple.Foundation 0x90a281d8 _decodeObjectBinary + 0x6f0
Aquallegro
music theory, ear training software
Version: 4.7
Crash on Launch in system 10.3.9
Feedback Type: Commentary
Contributed by: JohnnyHands Sunday, June 11 2006 @ 06:00 PM PDT
Product Platform: MacOSX
Used Product For: Less than a month
Recommend Product: NO
Comments
Crash on Launch in system 10.3.9 - andyvn22
Aquallegro requires Mac OS X v10.4 or later.Monday, June 26 2006 @ 08:20 PM PDT
Crash on Launch in system 10.3.9 - andyvn22
Aquallegro requires Mac OS X v10.4 or later.Monday, June 26 2006 @ 08:21 PM PDT
Crash on Launch in system 10.3.9 - andyvn22
Aquallegro requires Mac OS X v10.4 or later.Monday, June 26 2006 @ 08:22 PM PDT
Crash on Launch in system 10.3.9 - andyvn22
Aquallegro requires Mac OS X v10.4 or later.Monday, June 26 2006 @ 08:22 PM PDT
Crash on Launch in system 10.3.9 - andyvn22
Aquallegro requires Mac OS X v10.4 or later.Monday, June 26 2006 @ 08:27 PM PDT
Requires 10.4 - andyvn22
Aquallegro requires Mac OS X v10.4 or later.Reply to This
Monday, June 12 2006 @ 05:50 PM PDT