HTTP error when uploading pictures

First of all, I am pretty low tech (or compared to the average population, medium). I use my website as a blog, and have not added anything sophisticated to it. I pretty much just upload pictures and write text.

I am getting an error message when I try to upload pictures. The pictures are just regular photographs, and don’t appear to be too big. I have tried multi-file uploader and browser uploader. I have tried firefox and internet explorer. I did nothing new to the website. It did permit a few pictures to go through, and I am not sure why they were different – relatively the same size. The images appear to upload, and then at the point when a thumbnail would appear, a red HTTP error message shows up. I looked at other forum topics, but they seem to have more elements than my situation does (for example, I did not just upload a new version of word press and I have not made my own template).

This actually happened once before, and it just went away. This time it does not seem to be going away.

Please keep your advice simple. I appreciate it.