USB Ports Getting Blocked

Hi,

I am running an XP Home Environment. This morning I had a "blocked" USB port. I say "blocked" as I do not know how else to describe it.

I have a USB keyboard, and it just would not work, but it was powered on. The keys would not function. I tried it in a different USB port, and it worked. I was thinking USB port is broken.

I removed the keyboard software and re-installed it, and this solved the issue.

However, my question is what causes this, and how do I prevent it happening? It is the second time it has happened.