This has nothing to do with the bootloader, don't touch it unless you know what you're doing!
A 64Mb device can run any NC.
You may want to upgrade your NC to 9.051 or 9.151 which has proven to be a good NC for x10 devices.
Hopefully that will solve your problem, but keep in mind that you need to have lot of satellite contacts to update your exacte possition.
Somethimes this is not always the case and the update might not be within seconds.