Alot of people apparantly have had problems with this error when installing itunes or an ipod. I know that there are a lot of different opinions on how to get around this the simple one or at least as far as I have found is this: If you get this error open up your task manager by right clicking the taskbar and clicking on open task manager. There you should find a process called msiexec.exe. If you end this process and then re try installing iTunes and it should work. Same goes for the ipod software as the process re starts every time you turn on the computer you may have to end it more than once if you are not doing both installs as once. After you install you don't have to worry about it as it seems not to interfere with anything once they are installed, hope this helps