I site I've just finished developing was launched yesterday, but there were some reports that the main banner image wasn't displaying. The image was called banner.gif, and after recreating the image (to check it wasn't corrupt) and trying a jpeg version it finally turns out this was getting blocked by Norton Internet Security.
Now, this strikes me as being incredibly stupid and pointless on the part of Norton (aka Symantec). They're trying to block banner ads, yes, but by filename?!?!?! Correct me if I'm wrong, but if you had banner ads that you suddenly found out couldn't have banner in the filename, wouldn't you just rename them?
So what's the point in blocking by filename? All they achieve is potentially breaking the look of a lot of sites, as I'm sure banner isn't an uncommon thing to call the banner image for a site, and causing poor web developers a headache until they figure it out.....