Boot hangs with usb HDD connected

I have a toshiba 3Tb usb hdd for backup.

Like the title says the boot hangs if it's attached.

I just changed machine and reinstalled windows, and it still happens. It hangs just after the blue Windows appear.

It is marked INactive.
The boot order in the bios is SSD first (usb 2nd)
I can't see any sign of any system on the drive and I can't think I ever installed one

(older forumites might remember I posted the same query on sevenforums which never got resolved. This is a replacement PC of the same general type (dell T3400), but but with win 10 v1909 installed (somewhat to my regret esp WTF have they done with local networking but that's not why I'm here)
Any ideas please

Thanks for the quick reply. screenshot below

I don't know mbr/gpt, how can I tell?
It is only used for data backup
and yes have swapped usb sockets

thomaseg1 said:

Why are you showing so many removable drives with no media?
Are you running off a Usb Hub?

The pc comes with a "hub" built in on the front panel ( USB, SD, CF cards).

The disk in question is however attached to one of the USBs on the back.

I posted the same query on sevenforums which never got resolved. This is a replacement PC of the same general type

Different PC & different OS & problem persists... just a guess: the problem can be caused by faulty usb/sata external enclosure. Test reboot with ozher external disk/enclosure attached.

thomaseg1 said:

Thanks , that was next up on suggestions.
The fact that it is showing after the no media in the drive letter list
suggested it may be faulty.
Check disk might show the interface failure, then maybe not.

It seems reliable. It's used for backup constantly, and I have restored a couple of files without problems

Chkdsk seems happy

Stage 1: Examining basic file system structure ...
360448 file records processed.
File verification completed.
48 large file records processed.
0 bad file records processed.

Stage 2: Examining file name linkage ...
5 reparse records processed.
398104 index entries processed.
Index verification completed.
0 unindexed files scanned.
0 unindexed files recovered to lost and found.
5 reparse records processed.

Stage 3: Examining security descriptors ...
Security descriptor verification completed.
18829 data files processed.
CHKDSK is verifying Usn Journal...
8895288 USN bytes processed.
Usn Journal verification completed.

Windows has scanned the file system and found no problems.
No further action is required.

2861585 MB total disk space.
2207299 MB in 329768 files.
215296 KB in 18830 indexes.
0 KB in bad sectors.
1528060 KB in use by the system.
65536 KB occupied by the log file.
668246112 KB available on disk.

32768 bytes in each allocation unit.
91570751 total allocation units on disk.
20882691 allocation units available on disk.