Thanks for everyone's input so far.
I checked the 2 links and they worked fine this morning.
Next time it happens again I will retry those links.
If they don't work as well then it's some problem from my side.
I also tried to open images from some 2007 threads and for some the issue occured and for some (but less) the issue did not occur.
I guess the error got fixed somewhere in 2007 and thus not all from 2007 is affected.
Nonetheless I'll keep an eye for it, as some say it's also showing up in recent threads.