Hi CalvT, I must confess I'm stumped.
As far as I know the time between the manufacturer's logo and the windows logo should be used to determine what to boot and basic HW tests to determine everything is there and working. I thought it might be trying to look for something else to boot but if you deleted all partitions on the disk and network boot has been disabled I have no idea what it's trying to do. I assume it's not a HW fault or an incorrectly connected cable and you didn't open up the PC and start messing around at random.
I don't know what to think, sorry!
Let me know if you figure something out though, I'd be interested to hear what the issue is.