Crashes caused by file copying on these devices are usually due to the presence of third party background apps or drivers that need to be updated for NVFS compatibility. Palm's new Non-Volatile File System (NVFS) features some unfortunate behavior that causes many older background apps to crash after accessing more than 9MB of data since the last soft reset.
First, if you are running TealScript, TealLock, TealMaster, or other background apps by other manufacturers, make sure you are running the latest versions.
Next, try turning off all your drivers, background apps, and hacks to try to narrow down which one is crashing. The "System Memory Test" feature of TealMover may help to try to track down any applications that might still require patching. When you find a problematical app, you might be able to fix it by using TealMover to lock the file in memory using the "lock count" feature on the info screen.
Lastly make sure you have the latest NVFS patches for your device: As of this writing, the Tungsten T5 1.1 Update is available at
http://www.palmone.com/us/support/downloads/tungstent5/tungstent5update.html
and a various Treo650 and LifeDrive updates are available here:
http://www.palminfocenter.com/view_story.asp?ID=7913