Agreed on the last. :-(
I was getting some data off a couple of hard drives from a PC that died via an IDE to USB interface on my work PC a week or two ago. Everything was going Ok until I tried to get a clicking drive to start up again. No go, no go. I figured I had nothing to lose so I opened the drive and spun the platter around while it was trying to power up. To my amazement, it eventually spun up and Winders got about 2/3 of the way toward recognizing it, but didn't assign it a drive letter. At that point, the Winders desktop locked up. I gave it a few minutes, then didn't have much of a choice but to turn the PC off.
I turned the bad drive off, but left the USB interface attached, and rebooted.
The work PC then wouldn't boot up. Or it did, but it was ungodly slow. Even getting through the BIOS screen was ungodly slow. I thought, "Uh oh! What have I done now!" An hour or so of troubleshooting followed...
Long story short, it was trying to boot off the non-existent USB hard drive first. Unplugging the USB hard drive interface from the PC returned everything to normal.
I'd like to have that hour back, and all the earlier ones wasted on things like that. :-(
Sorry that VBox isn't being nice to you. :-( It has almost always been pretty painless for me. I was using 4.3.10 before I upgraded to 4.3.20 - I haven't tried to put 4.3.20 on a new machine, myself, but I don't know why it wouldn't work as 4.3.10 did.
Cheers,
Scott.