[Sussex] Sylpheed C+P Problem - Help?

[Adam Smith]

I'm hoping someone can help me with what is probably a very simple problem.  I've got the strange problem whereby I can copy and paste from Sylpheed for the first few attempts but then it stops working - i.e. nothing can be pasted into any other app.  It usually stops after about 5 goes, but if I close Sylpheed and start it again c+p works normally for another 5 or so times.  Although it's only a minor niggle it's rather frustrating :-(.  Can anyone shed any light?

Thanks
Adam Smith