No text on application windows

Good Morning,

This is my first post, been a mac user for over a year and the company here has two Intel Mac Pros, 1 Intel Mac Mini and one G5 Xserve.

One of our designers is suffering a weird problem that I have not come across before. There is no text showing on a couple of applications (Sigil and Calibre) they have downloaded, however, if you install the same applications on the other mac they are fine.

I'm not sure what is up, but I have attached some screen shots to this post.

Hope you can help,

Andy

 

They are both running the latest version of 10.6 (10.6.8?).

I haven't tried another user account as there is only one user at both of these machines. I will see if this has an effect.

One point to note, when we purchased these machines, a firewire migration was performed from their previous 10.4 G5 predecessors.