problem is propably identical to this forum post about NB6.7:
http://forums.netbeans.org/post-42860.html

Problem:
When i tried to open project properties of a freeform or nbandroid project, nothing seemed to happen:
no dialog popping up, and focus was still on the main netbeans window.

For "regular" Java Project types like "java se" and "java me" everything worked normal, i.e. the properties window appeared as expected.

Probable cause:
I use my laptop display in combination with an external display.
Because of changing workspaces, the external monitor sits sometimes "to the right" and sometimes "to the left" of the laptop display.

Netbeans seems to "remember" the position the dialog was on before, even if that position is not visible with the current display configuration.

Workaraound:
As soon as I "switched positions" of my displays, the missing dialogs appeared on the display that did not contain the main netbeans window.

I suppose Netbeans needs to check the position of Dialogs to make sure they are valid in the current display setup.