I've just uploaded a fix to this for version 3.0.6.0.
To see the fix, you'll have try it from a computer that hasn't already downloaded the web plugin, or you can reinstall the plugin directly from the following link:
http://www.millisecond.com/download/np/3_0_6_0/npInquisit.exe
If you simply revisit your launch page from a computer than has already run the experiment with Chrome, it will simply reuse the previously downloaded version of the plugin rather than installing this update.
Let me know if you still see any problems.
Thanks,
Sean