HP 8530w won't boot with external (usb 3.0) hd connected

Hi,

When I try to boot my HP 8530w notebook with a Seagate Expansion Desktop 3TB USB 3.0 harddrive connected to one of the USB 2.0 ports (notebook doesn't have 3.0) it won't get past the bios/dos bootscreen with hp logo. Only when I unplug the harddisk from the usb port it will boot. The disk is succesfully detected in windows 7 and working fine.

I've tried the following things with no avail:

- upgrade bios, now running version 68PDV Ver. f.20
- change bootorder in bios
- disable/enable legacy support in bios
- disable security options in bios
- formatted drive to ntfs/exfat
- installed all windows updates
- deleted and reinstalled usb root hubs
- using other usb ports

I'm running Windows 7 Enterprise 64-bit. My USB 2.0 400 GB freecom external hd's do not have this issue. I am clueless; is this a know issue and are there any additional things I could try to fix this?

Thanks in advance!

- Mike