XymonPsClient: column xymonlog goes purple

Hello everybody,

I'm going my first steps with xymonpsclient and I my first experiences are good, it just does what I expect.
But, on my first test machine, the column xymonlog has changed to purple, but the xymonpsclient is still running - I cannot see the reason for it to be purple.
Can anybody point me to the reason for this?

Regards
Christian