Images not displaying on website when viewed from computers other than my own

I’m hoping that someone out there can help me..

Ever since I upgraded to version 3.7.1 I have had issues with uploading photos to my website. I can upload images to the media gallery (although it says there is an http error). However, when I attempt to add an image to a page in the visual editor it is invisible. The curser moves over as if there is something there, but when the page is saved and viewed there is only blank space. In the text editor the code for the image is visible.

I asked for help with this and have tried the following suggestions:
– switching to the default theme to rule out any theme-specific problems (this did not help)

– resetting the plugins folder by FTP or PhpMyAdmin. Sometimes, an apparently inactive plugin can still cause problems. (This did not help)

– re-uploading all files & folders – except the wp-content folder and wp-config.php & root .htaccess files – from a fresh download of WordPress. Make sure that you delete the old copies of files & folder before uploading the new ones. (after this, the images were still invisible in the visual editor mode, however were finally showing up on my website!)

I thought all was fixed however when I viewed the website again from my home Mac laptop, as well as my Samsumg smart phone the old issue was back – blank spaces where images should be. I completed the above on my work computer which is a PC.

I have just checked the permissions – the WP content and uploads folders are 0755 and all the images are 0644.

I really don’t know where to go from here – can anyone help me please?

In summary – images are only visible on my website from the computer from which they were added!

Thanks in advance.

A link to the page that has three images visable on my PC but not on my Mac
http://www.reactphysio.com.au/what-do-we-do/group-fitness-classes/