I ran into this problem on a Terminal Server configuration where the Adobe Reader X (AcroRd32.exe) process keeps using high if not all cpu capacity even after you close the program. After some searches I found this could be because the welcome screen that is opened when you start Acrobat Reader isn’t closed at all, the session stays active and keeps using a lot of cpu capacity.
I could not found a fix for the problem at this time , but there is a workaround that solves the problem. You can disable the welcome screen from starting with a registry key.
1. Open the regedit and navigate to: HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Adobe\Acrobat Reader\10.0\FeatureLockDown
2. Add a new key with the name: cWelcomeScreen
3. Add a DWORD value to the key: bShowWelcomeScreen with value 0
Now when starting Adobe Reader it will not start the welcome screen but also does not uses the high cpu.