In the source code file sdcc/debugger/mcs51/cmd.c in the fuction(Next line)
static int commonSetUserBp(char *s, context *cctxt, char bpType);
And in line 1081 if (!applyToSet (functions, funcWithName, "main"))
If this line execute, the stack will be screw up, because the function applyToSet only has 3 arguments.
Fixed in svn revision #7834.
Borut