You called the monitor via break (see the b* in the first line). The program counter (pc) is $0073. This is at the CHRGET routine. This as called to read the BASIC text or a direct line from the input buffer. This routine is a copy from $E0F9. But it seems you have bad RAM at the zero page. So the copy of CHRGET is lost and with the data byte $00 at $0073 the monitor is called.
Have a look at you DRAM!