In Tools » Options... » Browser » File List, you can deactivate Recognize only by extension and set Scan file headers in folders to Always. Would you please try if that makes any difference?
Are you abkle to open/view these JPEGs with other applications?
Have you tried running XnView with its default settings by renaming xnview.ini to something like xnview.bak?
(You can look up the location of XnView's configuration file by going to Info » About....)
Could you upload one of these JPEGs to a free hosting service like ImageShack/TinyPic or directly to the forum as an attachment?
(Feel free to send me a PM or e-mail, if you prefer not to post the image openly.)
Wikipedia (XnView » [url=http://en.wikipedia.org/wiki/XnView#Versions]Versions[/url]) wrote:XnView MP (XnView Multi Platform) will eventually replace all other versions of XnView (*nix and Mac OS X and Windows) using the same source code for all platforms. It is intended to have a unified look and feel using the Qt interface. It already has full native unicode support and has the ability to load full bit depth pictures (8/16/32 bits per component) while also having better handling of language translations (text based files) along with an improved database. Currently the latest XnView MP version is 0.51.