5-Level Agreements?

Here's a situation that is not all that uncommmon, but caused a bit of a stir at our online table recently. Each of the four players involved had different opinions of what 5-level bids should mean in this sequence:
1S-1NT*-3C-4S**-?
*-forcing
**-the 3 card limit raise

What agreements to you play here? How would you handle this hand (the one actually held at the table)?
KQxxx
void
Axx
AKQxx