I have had problems since upgrading to Java 7 as well.
The most prevalent of which are objects disappearing or moving to a random location on the screen when I try to change the Z-Location of the object. This happens so frequently that now I save prior to performing Z location changes.
Additionally sometimes the Duplicate function does not work correctly.
There may have been others, I will keep track and post in here as I find issues.
I am currently running 7.4.2 with the latest version of Firefox on a WinXP VM that is running on a Windows 7 Machine.