The AVG Free Antivirus program's definitions went a bit wonky (technical term) today and it decided that every single portable app launcher contains a trojan. Rest assured that this is just yet *another* issue with a free antivirus program's virus definitions and there's nothing wrong with any of the portable apps. As for what to do to fix the issue, you should contact AVG and ask them to fix their mistake. Don't click 'Heal' as, to AVG, that means 'Delete the file'.
Update Sep 12 - AVG has already confirmed that this was an issue with their morning virus definitions update and has released a new definition set that fixes this problem. Also, from AVG: "If you need to restore deleted files from AVG Virus Vault you can do it this way: open AVG Virus Vault (Start -> Programs -> AVG Antivirus -> AVG Virus Vault). Locate the file that was removed, right click on it and choose "Restore File(s)" option."
Update Sep 13 - Looks like Kaspersky is now having an issue with false positives in all NSIS-based apps. Same trojan. They've been informed of their issue.