"Corrupt JPEG data: 117 extraneous bytes before marker 0xd9"

I don't know which jpeg image is the problem, I see this message about half of the times I come here.

Where does the message appear ? What software are you using ?

I'm seeing it at either the main UM page or the top level forum page, when it happens. Firefox opens an error window to tell me, other browsers display a similar message on the page itself.

Does this error come up every time you view these pages, and does it give a specific filename of the image file it thinks is corrupt ?

A screenshot of the error would be really helpful here, would it be possible to take a screen grab of the error dialogue box ?

Thanks.

Not every time, perhaps about half the times. No specific filenames are mentioned. I'll try to send you a screenshot when I notice the phenomena repeating.

Chances are that something in your cache is corrupt. Delete all your temporary internet files,

If you have Firefox > Tools > Clear Private Data > Untick everything but Cache > Click Clear Private Data Now
If you have Internet Explorer > Tools > Internet Options > Click Delete files button

Hope this helps

Have you updated all your Windows and IE Patches (or Firefox)

Perhaps you have a piece of spyware interfering with it. Or its quite possible that your Cache is interfering with it. As Gavsto said, delete your cache.

And I suggest running a spyware scan to. Its likely that you have some spyware that is interfering with your browser.