I just talked with the firmware developer. Is it possible, that you have a lot of sample files on the flash memory? The error message is probably not caused by the filterbank editing but because the near memory is exhausted by a large number of samplefile references and names.
In case you have already updated your Spectralis to version 1.50 please create a PERFORMZ.00x folder (where x stands for a number that is not used yet) and put the song with the problem patterns into that folder.
Now switch to the new PERFORMZ.00x folder in the memory menu and try your patterns. Do the still crash the Spectralis?
Now you can copy samples into that folder, that are in use in this song. It should work fine if the samples have no errors.
If you have tons of SLI and SLC files in the normal working directory I would delete everything, that is not in use in any song. The Spectralis can not be compared with a computer. The limited ressources are not capable or organizing hundreds of additional files. You should remove everything you are not using and you should work with multiple PERFORMZ folders.