Ext Designer is not working...

i am the person who've got licence on Designer

※symptom

i activated Ext Designer by open Ext Designer.exe or open .xds file

and then 'Welcome to the Ext Designer' popup shown.....

next i choose Recent project or New Projects(Ext JS 4.0.x)

------> popup disapeared and then nothing ....

untill yesterday(20140521). i had worked...

suddenly it's not working...

please help...

1. i tried reinstall

2. i tried windows restoration

Ext Designer'd run with sencha-3.0.2.288.cmd