Hello Chinoy11,
This is Kevin from palmOne. This could be the result of one of your VersaMail databases becoming corrupt. There is a step-by-step article for resolving this in the palmOne Knowledge Library article "VersaMail crashes or resets Treo 650" which you can read
here.
If, by chance you have a Sprint Treo 650, there is an update that addresses this issue, which you can perform from
here. Please note that this Treo 650 Updater 1.08 is only for Sprint branded phones and not compatible with other handhelds.
Sincerely
Kevin