A sweet friend, Habachur Hachashuv Meir Zev Steinmetz, emailed me a great kashya that the achronim ask: We know that one does not receive malkos on a לאו הניתק לעשה - if the לא תעשה can be "fixed" by doing an עשה. So one doesn't receive malkos for stealing because it is ניתק and fixed by the עשה of returning the stolen object. Why then can one EVER get malkos if he can fix every aveira by doing the mitzva of tshuva. Every לאו is ניתק to the עשה of tshuva!
There is much discussion surrounding this question. The Satmar Rebbe [I quote Rav Kook so often - I have to give Satmar a hearing as well] in his sefer on the yomim noraim [תשס"ט] answers based on a חתן סופר [the grandson of the Chasam Sofer] who says that an עשה can't perform two different functions such as both fixing a לאו and overriding [being דוחה] a לאו.
The gemara says that tshuva is דוחה a לאו [that Hashem takes us back even after we were unfaithful and married other gods while a husband must not take back such a wife]. Therefore it doesn't have the power to be מנתק the לאו as well. Hence, the malkos.....
There is much, much more.....:-)
לזכות ידיד נפשי ר' צבי משה בן שרה לאה לברכה והצלחה ובריאות איתנה