PM's not working

[Owen]

G'day Steve,
Just a heads up that after the upgrade PM's dont seem to be working.
I get

104 An Error Has Occurred!: Unable to open 1.txt

Possibly a permissions problem?

cheers,
Owen

[imported_admin]

Working fine fo me, sending and receiving.

1.txt has nothing to do with PM's

Have sent you a test PM

[Owen]

Got your PM and was able to reply.
I got the error whilst trying to reply to a PM from someone else.
I'll try again now.
cheers,
Owen