So there I was, in a rush to get to work... my screen wash fluid had run out about a week ago, so I decided to fill it up.
Bear in mind I've just recently passed my driving test (September 2005), and I knew the location of the various caps under my instructor's Corsa bonnet.
A few moments after pouring the new screen wash fluid into the cap, I realised I had been pouring it into the brake fluid reservoir.
So, my brake fluid is now contaminated with screen wash fluid. My own fault I know, but hopefully I'll resolve it...