I think that the tga image files are only downloaded if they are not already present on the machine, and are science-application and version dependent. The 7.28 in the filename implies that the machine has been assigned an MCM version 7.28 task, so I deduce that no other MCM 7.28 task was present on that machine at that time. This could occur if the machine had previously completed all 7.28 tasks and the cache contained only 7.29 tasks, but then received a 7.28 repair job.

You could check whether the other machines that are not seeing this problem have tasks that do not fit this situation and so have no need to download the image files. If this does accurately describe your situation, then it looks as though the process or server(s) that host the image files are having a bad time at the moment, but that task files can still download (same or different servers, I don't know).

The change from MCM 7.28 to 7.29 occurred yesterday 13 March.

[Edit] I can't explain the 28 Feb start that you report. Clutching at another straw, do you have a manual firewall configuration that doesn't like the new content delivery system?

Found the issue - we have a content filter appliance (ironport) that was blocking the new content management system's IP address.

Thanks Tony for the suggestion, and a Happy St. Patricks Day too yee!