As per GLLHG's post, all too normal I'm afraid.
The two main issues, created by our damp climate, are the pads sticking to the disk ad the disks themselves getting surface rust on them. This is only noticed on cars that don't get driven regularly.
Driving the car should take the surface rust off the disk; however, the pads sticking can create more annoying issues. As GLLHG said, upsetting the ABS sensors but also creating high points on your disks (you'll hear a rubbing that increases in regularity (for obvious reasons) as you increase your speed. This is thanks to the pads rusting to the disk and leaving a pad sized raised rust deposit.
GLLHG's avoidance techniques are all ones I use.
