Why am I getting virus warnings on old jpg's?

I have Avast 4.8 home edition build Jul2008 (4.8.1229). Avast is set to always look for program and virus file updates.

Just a short while ago, with only Avast On Access runnin’, 3 jpg’s in a storage folder, jpg’s that I saved a long time ago, got something like the followin’

Malware name: Multi:BinaryIframe
Malware Type: Virus/Worm
VPS: 081014-0, 10/14/2008

Before tellin’ Avast to go ahead an’ delete the first one, I went into the folder and highlighted the file. No thumbnail would show in the area to the left. I tried to open the file an’ got “Can’t read file header! Unknown format or file not found!” I checked the right click/properties on one of 'em and got this.

Created: Tuesday, March 18, 2008, 11:19:00 PM
Modified: Saturday, September 02, 2006, 9:29:57 AM
Accessed: Tuesday, October 07, 2008, 5:22:59 AM

What’s goin’ on? Is there somethin’ invadin’ my system an’ plantin’ viruses in my saved jpg’s? Or if they were like that all along, why did Avast only just now see them?

EDIT:
I just thought to add that the reason the files are bein’ accesses to start with is because I have a duplicate image detector runnin’. Apparently, when it accesses the files, that’s when Avast On Access Protection sees the bad files. Still doesn’t explain how those files got a virus/worm in them to start with

First - Deletion isn’t really a good first option (you have none left), ‘first do no harm’ don’t delete, send virus to the chest and investigate.

I would be suspicious of the detection more because of the malware name, Binary Iframe as iframes are more an html file issue.

There have been exploited jpg files in the past and also some files masquerading as jpg files, so it is worth further investigation.

You could also check the offending/suspect file at: VirusTotal - Multi engine on-line virus scanner and report the findings here. You can’t do this with the file securely in the chest, you need to extract it to a temporary (not original) location first, see below.

Create a folder called Suspect in the C:\ drive, e.g. C:\Suspect. Now exclude that folder in the Standard Shield, Customize, Advanced, Add, type (or copy and paste) C:\Suspect* That will stop the standard shield scanning any file you put in that folder. You should now be able to export any file in the chest to this folder and upload it to VirusTotal without avast alerting.

If it is indeed a false positive, see http://forum.avast.com/index.php?topic=34950.msg293451#msg293451, how to report it to avast! and what to do to exclude them until the problem is corrected.

Update, I have seen another topic relating to this, http://forum.avast.com/index.php?topic=39294.msg330083#msg330083 and it looks like this detection may not be good and could be a slightly mangled image file.

So my comment about deletion is very apt you could have lost some image files if it turns out yours are not good detections.

Much thanx for your replies! I’m about to shut down for the night, but I’ll take a look later!

You’re welcome, hopefully this will be resolved soon.