Hard drive will not show on "my computer

I have a strange problem that i have not seen before.
The PC i am working on has 4 HDDs installed but only 3 will show in "my computer".
If i use Easeus it shows all 4 and tells me that disk "New volume E" is a Primary system disk but the OS is loaded onto Disk "C" and there are no options to make this disk "E" active and show up in my computer,Device manager also only shows 3 HDDs and yet Speccy shows all 4.

Any ideas please???
Bill

 

The disk shows in management and shows it to be empty.
In Bios all 4 disks show and this one is number 3 in boot order.
The only OS on this PC (It's mine) is Windows 7 pro sp1

The reason it has such large storage is i intend to move all my documents and correspondence from external to internal storage.

I can not unplug the drives for the moment as the PC is standing on the floor and i can not lift it to the desk (when help arrives i will try it)

 

I suspect there is a problem with the Partitioning. The E is not in brackets and has no colon after the drive letter. Unless you have data on there I would suggest that you delete and recreate the partitions then reformat.

 

You got it in one thank you.
I used disk manager to change the letter (to W) and it shows up straight away.

The reason i need it is over the years i have hundreds of GB (probably thousands) of correspondence concerning my business and other files folders and photos stored on disk or flash drives and i am organizing myself to make easier access when i require said files.

Once again Thank you.
Bill

 

Is your optical drive labeled e: by any chance? I did wonder whether there was possibly a drive letter conflict and I have seen this at work where we have loads of mapped drives and windows cant allocate a drive letter to a USB memory stick. I thought windows would be smart enough to allocate a free letter to a physical HD though.

 

Yep that was the reason.
I feel just a little bit silly now as i should have seen that :-o

All is now good so i can get to work categorizing.