I got the issue that i can´t install the additional content "Loops & One Shots". After downloading the 3 installation files (part1 - part3). I start to run (as admin on win7 64bit) the first part...the extracting starts ´til the message coming up with "Error code 2: Can´t find part3".
I´d tried it another three times...same result...even by putting the three files in an separated folder on the desktop...
The part3 file seems to be allright, ´cause I can run it ´til the message coming up "please extract the other parts first"...

Still sounds like part 3 is bad. If all three parts really downloaded correctly, you should be able to extract all the files manually into a single directory using a tool like 7-Zip and run the setup.exe.

Simply download the offending part and try to install it again.  Sometimes one or more parts get corrupted. 

...done.

It was corrupted, but I was wondering about it, ´cause I could open it by itself w/o any message.