This website is very helpful. Thanks a lot.
I give you a tip if you don't want to reinstall Gmat Prep and get new CAT tests. New mix of questions.
I use windows seven:
1: Type in the explorer address bar: %appdata%
2: Go to the folder GMATPrep\Local Store
3: Remove pretool.db. You can also save the file in a folder if you want to keep tracks.
4: Launch GmatPrep software
You will have a new set of cats.
I used this trick a lot to train myself.
Feel free to contact me if you have any problems or remarks.