ERROR: 1603 ocurred during installation

I was having this problem recently, trying to upgrade SV11 to built 521.
I am running Win 7 Pro and solved it using the following website.

You have to remove the locks on the folders once that is done it works

To find the right folders to un-lock wait till the installation fails and read the directory beneath the error, you may have to do this a few times to un-lock them all.

Update

If no message is given as to the folders that were the locked, then go to
C:\Users\<username>\AppData\Roaming\Sony
look at the log file which looks something like this “SCS_INSTALLER_14.log” (it will have a datestamp), open with Notepad.

look for something like this.
(use CTRL+F in Notepad and enter ERROR and then did find next)

” SetupWorkerThread: INSTALLMESSAGE_ERROR Error writing to file: C:\ProgramData\Sony\Vegas Movie Studio HD Platinum\10.0\Vegas profiles update.ini.   Verify that you have access to that directory.”

Go to the directory stated and unlock.

http://msdn.microsoft.com/en-us/library/windows/desktop/aa372835(v=vs.85).aspx