Web design & hosting forum: website images weirdness: advice appreciated.

Hi everyone. Hope very much you can advise me here.
For many years, I've had a number of websites running happily and trouble-free: my guide to the city of Chester, www.chesterwalls.info, my photography business, www.bwpics.co.uk and my handmade leather goods site, www.goodhiding.co.uk.

Last week, however, I noticed strange behavour with the disaply of images on the sites. Text displays fine but, on a typical page with a number of photographs, some will dispay fine, some will show only the upper part of the image with the rest as a grey box, and some will not appear at all, just showing instead a blue question mark. The images are definitely sitting where they should be on the server. If I hit the reload button three or four times, the images MAY appear but often do not. They're nothing fancy, mostly small jpegs and a smattering of gifs.

The problem is still there over a week later. I reloaded the entire sites to the server in case some sort of corruption had occured there, with no improvement. The sites, when viewed on my hard drive are fine, but when viewed online display this strangeness.

The rest of the web, email etc are fine and as fast as ever. FTP to the sites is also as fast as ever.

The domain hosts, Hostroute, deny all responsibility and say the sites look ok to them. My ISP, Plus Net, also say it's nothing to do with them...

Some clients tell me the sites look ok, others experience the same problems I am seeing... so what on earth is going on here? bwpics.co.uk and chesterwalls.info have been online for well over a decade and I've never experienced anything like this before. My living depends upon these sites and I'm going nuts, please help!!