Is getting the 'unstable' error considered the same as getting the 'error' message in Wprime?, and is it a valid sub?
These example subs all say 'unstable' in them.
http://hwbot.org/submission/2415146_snegovick_ucbench_2011_fx_6300_1143.6_mpt_score/
http://hwbot.org/submission/2402574_berazde_ucbench_2011_fx_6300_1096.2_mpt_score/
http://hwbot.org/submission/2414830_darklord12_ucbench_2011_fx_6300_1007.8_mpt_score/
http://hwbot.org/submission/2412635_rafa.prebianca_ucbench_2011_fx_6300_968.7_mpt_score/
http://hwbot.org/submission/2356500_electroneng_ucbench_2011_fx_6300_960_mpt_score/
Here is the fourth place entry in that category. It has no 'unstable' error.
http://hwbot.org/submission/2323148_nom_yeslinux_ucbench_2011_fx_6300_977.7_mpt_score/