I have an Advent usb splitter with 4 ports which is connected to a usb port on my PC. When i start up windows 8.1, typically, I'll have a mouse & 1 external drive connected & my 2 printers connected to the usb splitter although the printers themselves may not be switched on. During my login session, I might switch one or both printers. Everything is running ok & I can print ok.

However, on a few occasions I've started my laptop with only the mouse & external drive connected. If I then plug in one of my printers, I've found that the mouse & external drive have become disconnected. Despite the (obvious) fiddling around with all of the usb connections in case one they've become unplugged, my devices remain unconnected. Why is this? Up till now, I've powered off my PC & re-started it. All devices connected via Advent usb splitter now work.