[StewartR]

Hi Guys

Thanks for the replies. I tried them both and they didn't resolve the problem (see my comments below) but made me try something else which may indicate a root cause possibly

I tried turning on the MBox Pro (power by the external power supply) by itself, without turning the PC on. Doing this, the MBox Pro seemed to be fine. Its blue power light was solid and appeared to have no issues. So, I left it for a little bit and then a bit more and then eventually I checked on it after 90 minutes ... and the blue power light was still solid, no issues. So, sitting by itself, it seems to have no problems. However, as soon as I booted up my PC, the blue power light started flashing again and it had problems. I tried this a few more times and got the same result each time
So, does this indicate that the MBox Pro itself, as well as its power supply, are fine but there might be something wrong with my PC or its various drivers that cause the MBox issues (I have upgraded the MBox Pro firmware the other day as part of troubleshooting remember)? What communication happens between the PC and MBox Pro when the PC boots that could be a problem? Does anyone know what I can do to fix it or troubleshoot it further?

Regards the other excellent advice,

I tried the adjusting the clock source as suggested and had a little bit of improvement but not much. When the power light was flashing non stop and the MBox Pro was completely unusable, when I adjusted the clock source away from internal and back again it did indeed make all the ladder lights light up and the MBox Pro became usable again for a few minutes but then the blue power light went back to flashing on and off and became unusable again
I also tried running the MBox Pro without the power supply plugged in and just the firewire cable connected to the PC (when the PC was turned on). Alas, the MBox wouldn't power up at all like this; it seems to definitely need the external power supply

Thanks again,
Stewart