i think i found the source of the crash - i often hibernate my vbox (virtual machine) and also my ubuntu (the host machine) so it appears that the memory was garbaged. after revooting only the vnox all is normal now, no crash.
the one thing i cuold not understand is why i got the crash only when using Chromium and not in other browsers ?
the one thing i cuold not understand is why i got the crash only when using Chromium and not in other browsers ?