|Your antivirus is probably responsible for forcing you to delete the download; it's falsely identifying it as malware. You need to temporarily disable your antivirus whilst downloading it, and keep it disabled until you've installed it. Then re-enable your antivirus.|
Just make sure you download it from the official FullTiltPoker website to be sure that it's "clean".
After you've installed it, you may have to configure your third-party firewall (if you have one installed) to allow it to access the internet when you want to connect to FullTiltPoker for the first time.