Open Office exit at splash screen Win 7 64 bit

[zenigold]

I'm an administrator's school Lab.
I've 26 Pcs with Windows seven 64 enterprise.
I've installed SO and all applications (Open Office 3.2 included) on the first pc and then we have cloned the other HDs.
For some time all works great.
For many reasons now on 4-5 Pcs OpenOffice wont'start.
I can see the splash screen and no more.
I've tryed to solve uninstalling IE 9 and to reset the user's profile but is the same.
Also I've uninstalled with Revo OO 3.2 and installed the new OO 3.4: save situation.
I've also searched for a log file to see if there are some errors but I can't found it.
Is there anyone that can help me to solve this problem ?
Thanks in advance
Paolo