Background: You are deploying Exchange 2013 using the CU7 media and are attempting to run setup /PrepareAD.
Issue: You receive the following error: “[ERROR] Access to the path ‘C:\Windows\Temp\ExchangeSetup\dsaccessperf.dll’ is denied.”
Note: This error may be contained in the Exchange Setup Logs
1) delete the “ExchangeSetup” folder contained in C:\Windows\Temp
2) confirm the account you are using is a member of schema admins, enterprise admins and organization management.
3) check the checkbox of doom on the user account being used to run “setup /preparead”.
Conclusion: setup /preparead should now complete successfully
Additional thoughts: During my troubleshooting I tried giving Everyone-Full-Control on the ExchangeSetup folder and that did not resolve the issue. I verified the dsaccessperf.dll had Everyone-Full-Control on it as well.