You need to provide more details from your side, so that others can help you more easily. Which OS do you have ? Is it 32 or 64 bit ?
Have you tried running Infinity as an ADMIN ? Any Antivirus/Firewall blocking the tool from launching ? Disable or turn OFF any AV package, for the time being. Or, you can also try adding an Exception for Infinity.
If need be, you can also go through this ‘guidelines’ thread first, as posted by STN: