virtualbox.org

(excuse me for my bad english))
I have created VM with Windows XP guest OS (my host OS is Windows 7). It's main virtual hdd connected to primary master IDE. My host's CD-drive is connected to primary slave. Everything works fine.
I have bootable USB-flash disk with DOS installed. Using VBoxManage.exe i created vmdk-file that map my USB-flash to virtual HDD. Next i connect it to my VM as secondary master IDE. But i can't boot from this drive! Durin startup i press F12 (to enter boot menu), than select Secondary Master and get error message:
Start booting from USB device...
Boot disk failure
But my USB-flash is definitely bootable!
Then i remove all my drives and connect only USB-flash as primary master. And boot was successful. Next i add back my main virtual hdd (with winxp installed) as primary slave. And i can't boot from this slave. Only primary master IDE is bootable!
My VirtualBox version is 4.0.4 r70112.
Last year (when i used v.3.x) i had no such problems, i could boot from any ide channel...
What is wrong?

I just tested this with one of my own VMs, two Linux VDIs put on the IDE controller and had no problems booting the system from either port (pri master, pri slave, sec master). So can you attach a log of such a run where you have problems booting the second disk? Use the attachment feature of this board.

Mmm... Where can i find this logs?
PS: the same problem i have with my external bootable USB-HDD (not flash).

Right click on the VM in the list, there you can view the log and save it to a common location.

Here is my log )
Primary Master: Windows XP.vdi
Primary Slave: DVD-ROM
Secondary Master: usb_flash.vmdk - can't boot

I don't see anything wrong in the log. I compared some entries with mine and I don't see anything that could be the problem. All I can think of now is that USB RAW disk is not working as it did. Can you try it with a second VDI file instead, like I did? If that works, then it's a bug in the RAW disk feature. Report bugs in the Bugtracker (separate account needed). Always upload a log file and describe as detailed as possible what you do to get to this result. For future references, link the ticket back here in case others have the same problem and stumble upon this thread.

I created another VM (DOS-type) with another VDI-file (but i did not install DOS there because did not want to waste time) connected as primary master.
My host's DVD-ROM connected as primary slave.
My usb_flash.vmdk connected as secondary master.
The problem persists (
Reported in the bugtracker: http://www.virtualbox.org/ticket/8385
In any case, thanks for the help )

I was suggesting that you get another bootable VDI and test with that as secondary master and boot from it. If that doesn't work for you either, something else might be wrong.