Xorg at 100% cpu when screen is locked (after a while)

[Roderick Johnstone]

Hi

I'm seeing Xorg take 100% cpu, sometimes, when the screen is locked. 
Under that condition my password doesn't unlock the screen any more.

It doesn't happen immediately when the screen locks, but sometime later. 
Actually I've just turned the screen locker off to see if its going to 
happen without the screen locker on as well.

I'm using the proprietary nvidia driver 304xx-304.125 so I know I 
haven't got a leg to stand on...

.xsession-errors has:
QXcbConnection: XCB error: 3 (BadWindow), sequence: 31517, resource id: 
79691778, major code: 18 (ChangeProperty), minor code: 0

and if I strace Xorg I see:
--- SIGALRM {si_signo=SIGALRM, si_code=SI_KERNEL, 
si_value={int=809121587, ptr=0x54552036303a3733}} ---
rt_sigreturn({mask=[]})                 = 77929408
--- SIGALRM {si_signo=SIGALRM, si_code=SI_KERNEL, 
si_value={int=809121587, ptr=0x54552036303a3733}} ---
rt_sigreturn({mask=[]})                 = 77960128

for ever.

Anyone else on nvidia drivers see similar behaviour?

Thanks

Roderick Johnstone