JPG Attachment problems?

JPG thumbnails are not displaying properly. If there are a few then perhaps half will show. Also when thumbnails do show and are clicked on sometimes I get a "Sorry we can't display this attachment"; and sometimes when I click on a non-displayed JPG thumbnail the attachment appears. I don't know what's going on. I reported this to Yahoo! and got a canned answer which did not even remotely speak to the problem, though I did follow the instructions that were given. This problem crops up every few months and has been persisting for something like 5 years. I note that when I put a tracer on Y!Mail using cmd the third hop says "Request timed out". It seems there's something awry along the pathway. Could this be causing my problem? Any helpful answer is greatly appreciated. Thanks in advance.