Many Japanese players using Windows XP can't start MPTEST.EXE though some users can do it.
I found that this trouble was caused by selecting Japanese for Default input language.
I resolved it by following setting.
1. In Control Panel, click Regional and Language Options.
2. Click the Languages tab, and then under Text services and input languages, click Details.
3. Under Default input language, select English - US
MPTEST.EXE is now working well.
I don't know if this language problem is only related to Japanese.
Anyway, I hope that it would be fixed.