What's happened to my PPRuNe display format?

[Gertrude the Wombat]

It seems to have gone into some sort of tree-based display. I've checked my options and it's still "linear oldest first" so what's going on?

[BOAC]

Try setting it to 'Threaded', save and reset to 'Linear'. Strange things, computers.:)

[Gertrude the Wombat]

Worked. Ta. Oh well.