This is a weird one, the installer is creating a temporary folder to extract TeamViewerQJ.exe (does this on the normal TeamViewer installtion too), but generates the above error, when I checked with Process Monitor I could see that it couldn't get write access to the temporary folder the installer created. When I checked the permissions it had no inheritance set, but did have full access for administrators and 'special' for everyone (which was limited to listing the contents of the folder and deleting files and folders - hence why the installer through the error.
I've disabled AV, and it works OK when running as a full administrator on the box. I suspect it has something to do with the temporary folder being redirected to a network location and the API isn't setting the permissions correctly in this scenario, but any thoughts would be welcome!
Terry
Error:

Process Monitor - Access Denied Error:

NTFS - No Inheritance Set (So User Has No Access)
