A few more points worth noting:
Use NiMh batteries over NiCd batteries wherever possible. NiCd has a steeper discharge curve, which could lead to loss of data when the batteries are low.
If your usage is heavy , use NiMh rechargable batteries and get a charger from Radio Shack or someplace… this will save you an enormous amount of money in the long run.
It is possible that you lose data when you replace your batteries… It has happened to me a couple of times… In this case it’s not a hardware problem, just a spike that leads to loss of data…
from this excellent page :
http://www.pstec.de/ppp/ppppowpi/ppppowpi.html
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A final word on data loss: My speculation is, that a spike on the power supply of the Palm is more likely the reason for a data loss when changing batteries than a low voltage situation (unless there is a real defect) So IMO, changing the batteries one-by-one is not a good idea, as you have two times the critical situation of breaking supply and making ‘first contact’ again (no, your Palm is not assimilated …). Maybe the worst is, when you’ve a ‘shaky’ hand when inserting the last battery (no joke!).
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It is not possible for any software to cause a hard reset. Your power button must be physically depressed for this to happen.
Also, you are supposed to replace batteries within one minute of removing them… but you generally have a lot more time to do this… On pieces i’ve tested, data has been unaffected even though batteries were removed for upto 12 minutes… the capacitor supplies charge for this period…
So, in conclusion, and with renewed data in your last post, it is still possible that it is not a hardware problem, provided that the spike is what caused data loss the first two times, and NiCd batteries caused loss of data the third time.
I suggest that you test the time that your Palm m105 can stay without batteries and still not lose data, and if it can consistently do more than 5 minutes over repeated tests, then your capacitor seems to be intact and it is possibly a problem with the brand or composition ( e.g. NiCd ) of batteries that you are using. In this case, switch over to NiMh batteries (Duracell alkaline batteries are also good). If it loses data within minutes each time, then it is more likely a hardware problem and you should go in for the exchange thing.