This is WindowBlinds 7.3 bug... Look at the instructions which help you to solve a problem:
1. Press Start button --> then press Run
2. Paste a string: shell:::{80F3F1D5-FECA-45F3-BC32-752C152E456E} to the "Run" input box and press "Ok"
3. You'll see the "Tablet PC Dialog". Open the "Other" tab and press "Left-handed" radio button. Then press "Ok"
That's all. This will set all menus, submenus, context menus, etc... in Windows 7 to open correctly.
Best regards.