You should of contacted us via the
contact support much sooner, not sure why you waited 6 months to tell us.
Is there any specific reason why you haven't upgraded to Windows XP service pack 3?
I am fairly sure that FlashFXP 5 requires Windows service pack 3 to work correctly on Windows XP.
FlashFXP v4.x and older have reached their end of life (and the openssl library shipped with it contains known security vulnerabilities) and that is why the update check is forcing you to update to the latest version.
Perhaps you can also explain in more details as to what type of situations would trigger your PC to randomly reboot.