The problem with the Twain Complete Cover that you were trying to upload is that it is WAY too big! 3408×2556 pixels is 3.4 times the width of your site. It’s also 2.15 megabytes, which may take a while to render on uploads and would certainly take forever to download which may cause a bad user experience and Google penalties. The file is also high-resolution at 300 dpi, which is about 4x the resolution of web browsers. The standard most use is images set to 72 dpi (max web resolution) and 96 dpi, which gives you a bit more resolution if someone prints the site.
We usually strive for images of 10-15KB for “headshots.” (7KB is often possible) Content images can often be 50KB or less and the biggest images we use all have to be less than 100KB. The image you were trying to upload was 22 times our acceptable maximum.
Webpages look best when there are image standards used, such as only using 1 or 2 widths (or 3 at the most). Most ratios are 3:2 or 2:3 for vertical, but squares are pleasing too.
One other mistake most people make with WordPress is that they adjust to size and dimensions of their images using WordPress editor. DO NOT DO that! Always optimize images on your computer before uploading them. I imagine you were going to do this with the cover image, but that is bad practice. Also, images that are reduced without ‘sharpening’ do not look as crisp as those optimized using tools that are likely already on your computer. An investment in Photoshop Elements might be a good thing.
So I have optimized your cover images, reducing them to usable resolution and file sizes, as well as reasonable dimensions for your consideration and use. Once uploaded they no longer appear as grayed out like the monster file and all PDFs.
What are you using the PDF for? We only use PDFs for content the visitor may want to download and print.
Ok, so here are your examples!!
Here is the Twain Complete Cover at 750×563 pixels, 187k in size (less than 20% of what you were uploading) and 72 dpi…
Next, here’s 375×282 and 71k
The text on the left panel is a little difficult to read.
I made 2 sizes of the front cover for you too, 361×557 (81k) and 200×309 (51k)
For what it’s worth, the fonts on your site need to be increased. Many people recommend using a 14 pixel font. Some use larger. You have multiple fonts on your site for titles, captions image and the like. Your main content is default 10-pix. Would you like me to increase that?
The tech upgraded limits beyond what is generally set. Upload size went from 10-20MB. I see no reason why you’d need more than 10MB, unless you were offering a free download of a book or a big video file. In that case, I recommend using Amazon S3 instead. REALLY cheap.
Tech said part of the problem may be related to plugins, which may or may not be true, but the only way to determine is to turn each off individually and test to see if the problem resolves. I don’t really think that is an issue and don’t want to spend any time or money on it.
Another tip is to blow your browser cache every month or 2. I’ve seen all kinds of problems resolve if you do it regularly. In Chrome it’s found under History.
Your site needed to be upgraded to WordPress 3.6 and there were 7 plugins that needed updating. Again a change in plugins might have been an issue, but I think it was more related to file size. I updated WP and plugins.
“Confound the Internet, anyway. It is the very demon for conveying similarities of sound and images
that are miracles of divergence from similarity of sense.” Mark Twian
Of course, his best quote about the Internet can be found in Letters to Satan, “It is a time-saving, profanity-breeding, useful invention, and in America to be found in all homes except parsonages.“