USB not connecting

It's not a bug in Win 7, a good possibility is you need to reinstall the chipset driver from the manufacturer of your computer (motherboard) that should be the first driver installed after the OS.

Is it only with this one flash drive that this issue happens on all three computers? If so you may want to pull your data off of it ASAP and get a new one, it seems to me that this is likely an issue with the flash drive and not the computers

So this issue happens with any USB device on all three machines? What USB devices have you tried? Maybe try using a friend or family member's USB drive that you haven't tested before

Are your settings in the BIOS for the USB Configuration at their default settings?

Very strange, it seems unlikely that all of these devices would have some sort of issue, but equally unlikely that all 3 computers would have a chipset issue. Never assume that buying a machine from a well-known manufacturer will ensure a problem-free experience.

At any rate, it's easy to update the chipset drivers and then try again, which would be my first step. Also try using a couple of the problematic devices on a friend's computer or maybe your work machine in order to rule out the device as the source of the problem.

Additionally, are you using any obscure software on all three machines?
Have you tried stopping non-essential background processes and after-market software?
Have you tried booting into safe mode?
Are you plugging the devices directly into the machines and not some kind of hub?

Those are just a few scenarios to consider that may be causing the issue