(0. Place the file "LOVEISAV.SNG" (Daz will provide it here) on the top-level of the internal HD. Then switch of.)
1. Switch on and wait for the Oasys to complete booting
2. Press Disk-Button
3. Load "LOVEISAV.SNG"
4. Press sequence-button
5. Touch the song name (it should be the song 00) to open song-browser
6. Select song slot 02
7. Press the sequencer start button and play about 3 measures
8. Press the stop button
9. Press the program-button (you should see A000 Oasys-Piano)
10. Touch the "Keyboard" instrument button on top of the screen to open program-browser for browsing by instrument groups
11. Select the instrument group "Slow Synth"
12. Select A044 Whales World
13. Play a G-accord (G-H-D) for a few seconds
14. Press the cancel button while the sound decays
Now you should have a nice freeze. Sometimes it's accompanied by a typical digital fine tone - sometimes by black lines on the screen. But it freezes each time I follow this procedure (tried about 15 times).
Note: this procedure works with other sng-files as well. I've produced this bug twice using the factory songs and several times using other sng-files. But strangely it does not always work. With this file (and at least a second sng file I've produced) it works always.
It never happens if you press the OK-button instead of the Cancel-button which reminded me of a discussion here about better not to use the Cancel-button in the program- or combi-browser. Perhaps this procedure can help Korg to find out, why the Cancel-button tends to freeze the Oasys in some situations.
Oops - my Oasys config was missing:

OS 1.2.3
2 GB
EXs1/EXs2/LAC-1
No USB-devices connected at this test (well, to be precise: a USB-extension cable was plugged in - but just the cable - no stick or similar at the end of it)
Bottom line for me: I don't use the cancel-button anymore in the program- or combi-browser (which is not so nice - but overall time-saving
