janzokris, as said in above posts you need to clear your cache then download Plus!Live again from the official site or from a mirror. Welcome to the forums
For those using a downloadmanager: turn that off..it is known to corrupt exe files (it is good for downloading pictures tho).
I also have Plus!3 and Plus!Live on my website on files page, just choose "local" after you clicked the download button (main is Plus! site, local is my own).