I have the same problem. PODHD400 simply won't start up. it says "DSP boot failed" so i took your advice and tried plugging it in to the rear usb port in my pc, but when i try to reinstall the firmware/update the flash memory again, it wont let me because my computer says it is not connected. It's kind of hard to explain so i"ll do my best. My computer recognizes that something has been plugged into the usb port but when i look at Line 6 Monkey, it tells me that my PODHD400 is not connected, therefore i cannot reinstall anything or update anything. Originally it said there was an error in the installation and i was instructed to power off then power on my POD. Immediately after following these instructions, it just displayed the "DSP boot failed" message then went blank. I'm 99% sure this is the reason it is malfunctioning. Sorry if im sounding redundant, i just want to eliminate any possibilities f misunderstanding and/or misinterpritation. I'm scared... I love my PODHD400, and i would hate to lose it. Please help me...please...