Sounds like Magix is holding back some of your previous settings and locations of files and folders set up as the default locations or where you told it to find the soundpools from the first program MX.

In order for you to get a clean install and start fresh to then reset file and folder locations I know of only one way.

You will need to download and install a uninstaller program that will search for leftover files and folders not only in the install location but also the registry. If I were you I would go to Cnet.com and hunt down the free version of "Revo Uninstaller" install it and run it - the main window that starts up in Revo is the uninstall mode that shows you a complete list of all programs installed on your PC - double click the Magix programs you want and wait Revo will open a new window - in this window you will see that Revo is now making a backup copy of your registry and initializing the programs built in uninstaller - go through Magix uninstall process - when it has uninstalled you will return to the new window in Revo mentioned and click on the button in the window that says "Advanced" then click "Scan" Revo will now go and find every file and folder Magix did not delete - when the window changes and shows you a line-up of all leftover files in the registry then click the button "Select all" then click the button "Delete" - Revo will then search your primary drive for all files and folders as I suggest you do the same thing explained above by select all and delete.

I use Revo Pro for any program I want uninstalled just for this reason alone, I have used it for years now with no issues and it has saved me many times in similar cases like you are in now.

Then try reinstalling the Magix program and you should have no problems.

Hope this helps!