Window-borders / title bar vanishes frequently

[Heinz Diehl]

Hi,

recently, I installed Fedora 17 with XFCE on a friends laptop. All
works perfectly, with the exception of a little inconvenience which
happens from time to time: all the borders of all windows
vanish. Precisely, when you open e.g. the XFCE terminal emulator (or
any other program), the blue line at the bottom containing the word
"terminal" and also the +, - and x on the upper right corner and the
scrolling bar is no longer there (I guess it's called the title bar).
She's not able to move these defective windows either. Rebooting
doesn't help.

Opening a console/terminal and doing an "xfwm4 --replace" cures this
immediately - until next time. I found this in some thread about a
similar problem and tried it, without knowing what it actually does,
but it worked.

Frankly, I have not the slightest idea where to look for a permanent
solution. Does this phenomenon maybe ring a bell for somebody?
What could I do to get rid of this?

Thanks,
Heinz.