faulty mouse prevents computer from booting

[Big Jim]

Just sold a refurbished PC, the customer got home and said it wont work, sent me a picture of the screen showing intel network boot agent.
When I called round it was on boot selection menu, and there was a delay of around 10-15 seconds between pressing a key on keyboard and the screen/computer reacting
I selected the correct boot method and it didn't seem to be doing anything, so I quickly swapped the USB devices around just to check it wasn't a faulty port we had missed, and the computer had booted to windows whilst I was doing this, got in to windows and something wasn't quite right, and the mouse didn't seem to work, Red LED on bottom of mouse was flashing on and off when I checked it.
I rebooted the machine and plugged the mouse in to a different port just in case and it wouldn't boot again.
Unplugged the mouse and everything ran as it should.

Can't remember ever having seen this one before.
Very strange. and pretty lucky that I picked it up as quick as I did.

 

[GTP]

An unusual one I agree and well spotted.
I had a similar issue with a wireless keyboard a while back where pressing the space bar on the login screen caused the PC to hang for like 10 minutes. Kept thinking it was a windows problem.
Took a bit of head scratching and a wired keyboard to get it running right.

Replaced the keyboard with a Microsoft Wireless one and all fine.

 

[Sky-Knight]

USB busses can do some really strange things with faulty devices attached. I run into this usually on 3rd or 4th gen platforms on the USB 3.0 ports. Sometimes the drivers just don't quite work.

Certainly not a daily issue though, more like something I hear about a couple times a year, much less see myself.