I have som huge problems using GPS navigation on my x10. Initially I blamed Navigon for rebooting my phone after only a few minutes. But later on I exeprienced that using google maps over mobile broadband also reboots the unit. As a third test i used Runtastic in "car mode" giving the same reslut. Seems like som kind of buffer overflow when in fast movement as Runtastic works normaly when walking or running. I run Andriod 2.1, whitch is the last version for this phone as far as I know? have searched for uppgrades for the phone (and upgraded Navigon) taking it to the latest version. Someone experienced the same problems? Som suggestions for correcting the problem?
If you have an X10i rather than an X10 Mini or Mini Pro you should be able to update to Android 2.3.3 or Gingerbread...
Use either SEUS or PC Companion to update and back that phone up because it'll wipe it.
Personally I would think about a factory data reset, it could be a software glitch or another application causing this to happen. If a factory data reset doesn't fix it then it's likely a hardware fault.