Are you logged in as the administrator of your machine or does your Windows account have admin rights; without either of these there is a possibility of attempts to install programs will be denied by Windows.
Also, have you tried installing GMATPrep on other machines and do you get the same error?
Lastly, the error states it's a "read me" only one, there is the chance that the program did actually install. Have you checked to see whether GMATPrep is located in "C:\Program Files\GMATPrep\" directory? If so then click start, select run and copy paste the following (including the " " speech marks):
"C:\Program Files\GMATPrep\jre\bin\javaw.exe" -Dsun.java2d.noddraw=true -ms64m -mx256m -jar "C:\Program Files\GMATPrep\lib\GMATPrep.jar" "C:\Program Files\GMATPrep"
That will run GMATPrep automatically directly from the start/run location.
Hope this helps!
