If you see a post with a link to software that contains a virus, you have a few options, basically boiling down to:
If you believe the user did it unintentionally, point it out in a comment, and consider editing the post to replace the harmful link with a link to the clean version of the software (always use official sources for software downloads) if one exists, or perhaps editing the link out with explanation.
If you believe the user did it intentionally, point it out in a comment and flag the post for moderator attention.
If you believe it is spam, flag it as such.
Rarer case: If you know the user did it unintentionally but, say, the official source was compromised somehow, leave a comment then consider notifying the maintainer of the official site.
If you suspect the program is harmful but aren't confident enough to edit / flag, you can raise the issue in comments first.
As for your specific case, assuming you are talking about SecurStick, for what it's worth I don't really see any negative user reports about it on the internet. There's a few users who mention false positive virus scans. The four symptoms in your bullet points seem like either user error, bugs, or interactions with your antivirus. That is not to say that it's OK, and you should never use tools you don't feel comfortable with (I probably wouldn't use SecurStick myself), but you may want to raise it in a comment and do some research before you start taking serious action.