It's hard to say. This is the first report I've seen on these forums of this, so it may be worth at least quarantining.
On the other hand, McAfee and Norton are notorious for being overly zealous in their antivirus work -- not to mention often interferring with video editing work. In fact, many PC pro treat Norton's system care software as if it's a virus. There's a very elaborate process for removing it.
Most PC-based editors I know prefer Avast! or, even better, Microsoft Security Essentials. Both are excellent, FREE and non-intrusive.
Hmm... the OP does not say if this is from disc or download
If from disc, I wonder why an install file is left behind on the hard drive at all
If from download (this is to the OP... Original Poster) write a copy of all download files to DVD before you delete anything
I, too, use Norton (360) and have received these warnings since I downloaded the trial version of Premiere Elements 9.
I've read some reviews that suggest Norton can be overly sensitive. That's not, in my opinion, a reason to ever trade Norton in for a different virus protection. Their tech support is very helpful and our family has been using Norton on every single computer in this house since 1990. We are heavy internet users. So far, we have never had a virus incidence.
Also: I have owned Photoshop and Illustrator for nearly 20 years, InDesign for over a decade. Those programs have frequently beeen upgraded. Norton never once complained about any file in them. Nor did Norton complain about any file in the trial version of Web Design Suite or Design Suite Premium that I downloaded this year, (had to study both to decide which to buy).
So, the high risk warning on a file from Adobe did really surprise me.
I'd been working a few hours in Premiere before the warning popped up. So, I opted to just delete it then try to find something that worked differently with it being gone, (or didn't work at all without it). One can always re-download a program, (even the trial version if time is not up) or reinstall it from the disk.
So far, I haven't found anything that works differently without that file and nothing that won't work without it.
I haven't tried uploading anything yet and do really suspect that that could be the function of the file. Apparently, it has nothing to do with downloading. The auto update, worked just fine without that file.
I'll be leaving it off unless I find something that doesn't work without it.