It could be .netframework related too but since you had said you had reinstalled those, I did not touch upon it.
The next thing will be the Windows Installer.
Generally, this problem has baffled many to the point of accusing Microsoft not doing anything to resolve it. Some have stated that even a complete clean install did not resolve the problem.
So we will only be trying our luck, trying various fixes proposed by many.
Then again I had overlooked that you have a Windows 64bit system.
Go through this thread and especially one Kalidasan Ramadurai's post dated 27 July 2010 and check whether it helps. http://social.technet.microsoft.com/...6-98d25a207a6a
In the meantime - that is tomorrow, now it is almost time to hit the sack here - I shall continue to look for any other handle on this.
You could also search on means to uninstall and reinstall Windows Installer.
Please do make sure that you have created the Recovery Disks for your system.
EDIT: Also check this thread http://www.speechcomputing.com/node/3753
EDIT 2: Link to Kalidasan Ramadurai's post added.