PROBLEM images and css have text/html content type

[d2a]

just adding some social integration to my old GS site and noticed that tumblr integration wasn't working. when i try to add any image from my site to tumblr, it rejects the image, claiming it's not an image format it recognises (it's a jpeg, which appears in the browser fine). checking the header responses with curl -I shows all files (css, html, php, jpg, png) as having Content-Type: text/html; charset=utf-8.

Trying to add mime types to htaccess or whatever doesn't work, so i'm guessing it's either a getsimple failure or a webserver config fail. since it shared hosting i've no hope of getting anything changed there, so hoped someone here might know of a workaround or fix - thanks