Serials Suddenly Stopped

Why would the serial ports suddenly stop working? I’m using Angstrom 3.2.42-psp27 on the White. I’m programming with Qt 4 and qserialdevice. Muxes were all set up and working. I’m using ttyO1, ttyO2 and ttyO4. Using the example writer program that comes with qserialdevice, ttyO2 still works but ports 1 and 4 have gone - the program reports that it cannot open the ports. I haven’t changed the kernel or done an update.
When I echo and cat the ports I get the data through but I can’t figure out why I can’t do the same with a program on two out of the three ports.

I re-wrote the image to the card and it worked!