The problem is that Zaurus freezes
whenever I tried to change any setting .
I have a different model, but it is normal, at least with Sharp ROMs, for the Zaurus to freeze when is saving settings. Once the operation is completed, it should return to usable.
You didn't say how long it freezes, and that will be a clue as to what is going on. How do you know a normal from a serious freeze? Depends on a lot of factors, I guess you kind of learn from experience and asking around. I figure half a minute on my particular Z is okay...longer, I start to get concerned.
Sometimes my Z freezes up if I'm asking it to do too many things at once and one of the apps. seems to get stuck. Closing all other open apps before changing settings could help.