Aero theme failed after sysprep

After a sysprep I found that the Aero theme was not active, so, google is my friend and found, before running sysprep, type winsat prepop, this will create a copy of the Windows experience index in xml file and after /oobe will give you Out of the Box working Aero theme. Followed all the leads, but... what ever I try, after sysprep no Aerotheme, because windows has no experience index.
Yes the hardware is identical on all workstations.
Yes I run Winsat prepop in an elevated command promt before running sysprep.

What am I missing?

Usually GPU related like Magus indicated

Thank you for your quick response.
Yes sorry you are right. More info. I created an image on a dell optiplex 790. Included the experience index (5.1).Run Winsat prepop. If I rerun the experience index after sysprep it comes back up very rapidly (like it reads the xml files?) and then Aero is fully functional, but I have to deploy some 600 pc's and I dont want to run it on every pc. It read on forums it can work with the winsat command. It just wont work for me. Some say give it some time and it will run itself eventualy, but thats not the case here.
All hardware is Identical. In my unattend.xml I use the command to persist the drivers and I can see after sysprep the hardware is recognised and the Intell driver is applied. I really have no idee where to look next.

Run the Aero troubleshooter. Type aero in Start Search box.

Already typed aero and indeed after that it works, but I want Out of the Box working Aero after a sysprep and I just can't get it to work for me.
btw.. Its 600 workstation all together.. its a classroom situation and the largest number is 62 at once. I use GSS 2.5.1 so once the image is well prepared, deploying the image takes no more then 15 minutes.

Find out what Aero troubleshooter fixes and adjust that setting before SysPrep.

I remember something now. I created the image in sysprep audit mode.Before sysprep I give the command winsat prepop. After sysprep /generalize /oobe /shutdown /unattend:unattend.xml, I saved the image (symantec ghost). When the workstation is restarted it logs right back into the administrator account. It should ask for a password, so somehow the audit mode is not canceld?? Perhaps this is somehow related.. Needs further investigation..

Oke solved!
I probably did something wrong somewhere along the process. After sysprep /audit /reboot you also lose Aero.
After the sysprep /audit I re-runned the Windows Experience index. The Aero is enabled. Then gave the command Winsat prepop and finally sysprep /generalize /oobe /shutdown /unattend:unattend.xml
Then used ghost to create an image, deployed the image and everything was OK!
Aero functional, windows 7 activated, office 2010 activated, joined the domain, and put into the right OU. Life is wonderfull..
thanks for your help,

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