Mini6410...WinCE boot on SD but not in NAND

Hi,
I'm having a problem to boot WindowsCE in NAND flash...when the nand switch
is select on my mini6410 and i power it ... the bootlogo appear with the
progressbar. At the end of the progressbar loading i see some display
glitches (kind of lines) then hang there.But otherwise boot fine in SD
mode!!!

Any clues?

regards,
laurent

More precision on the board and OS...

Mini6410 w N43 display... 256 MB RAM w 1GB NAND Flash.
Windows CE 6 R3...

i m using WinCE6.0 R2 and 128MB RAM with mini6410