Any problems in Device Manager (especially with USB or Human Interface Devices related elements)?

It all appears ok there in Device Manager. What would I be looking for as a sign that something is wrong, Dan?

Yellow exclamation marks.

I have to be off now, I'll get back as quickly as I can, hopefully this evening.

I hope you don't mind me chipping in - check what Dan told you to check because it is important to check that the hardware is working before we look on the software side. If it is working fine, then we need to take a look on the software side. I want to check that Autoplay is enabled for your USB drives.

Plug both of your USB drives in.

Download TweakUI.

Install it and then run it. Expand:

• My Computer
• Autoplay

Then select the Drives option. Ensure that there is a check mark next to the two drive letters that are for each of your USB drives.

Next click types. Ensure there is a checkbox in "Enable Autoplay for Removal Drives".

If a checkmark is absent from any of the boxes I listed above, make sure you check it and then Ok it. Then Safely Remove your USB device via the system tray icon and plug it in again. I really hope this works.

Success with both! Thanks to all.
Fetch the chequebook, Jenkins...

Success with both!

Not so fast! What fixed it? If it was TweakUI, great! But it is important to note that all TweakUI does is make it easy to change Registry settings. If your flash drives worked correctly before, something changed and we still don't know what???

If something was changed in Registry it was probably changed by me. I was messing around with a couple of programs last week, I think the older version of HJT and jvPower tools, and I know I changed a couple of things. No idea now what, though.
The only other problem that's surfacing right now is the persistent bug that Neal has been helping with in another post.

So was it TweakUI that solved the problem?

It was.

It is extremely probably then that you did perhaps delete something by accident using JV16 Powertools, I'm glad your sorted.