There's a few threads on this problem in the forums, but there don't seem to be many positive fix responses so I thought I'd post my recent experience.
I recently bought a 2004 147 in lovely condition, a few weeks ago it started flagging a VDC/ABS error and disabling the ASR. It usually reset and would only happen occasionally. I started going through the forums looking for a solution, replaced the battery (it was due anyway) but to no avail. I decided I was going to replace the midi fuses, as a systems engineer I couldn't quite see this being the problem, very rare for a fuse to have a partial breakdown but it's a cheap thing to eliminate (if you can find them, ebay's your friend here).
One other thing I'd noticed was the car felt like it was dragging slightly as if the brakes were slightly on, I put this down to unfamiliarity, more on that later. While out scouring the area for fuses the front right brake jammed on, full ABS and the car dived right, quiet street thankfully. This happened two more times in the next mile, so, decided I'd take it over to HWM in Walton, the car was clearly unsafe to drive and that's an epically dangerous system failure. HWM are just down the road from me so fear of diving in to oncoming traffic overcame fear of main dealer pricing. I met Vinny, their service tech, who walked me through the wiring diagram, a fuse isn't going to cause the brake to jam on like that, it's clearly a sensor problem. Plugged in the computer and sure enough the yaw sensor error was flagged. We took the car for a quick test drive and with him in the passenger seat watching the computer the car braked again. Back to the garage, check it in.
Conclusion: The yaw sensor when the car was stationary was reading about 4 degrees off to the right causing the VDC to randomly kick in. Replacing it and two weeks of driving later not a whiff of a problem, there's also no feeling of dragging anymore. The dragging feeling looks also to have been validated, they checked the disks and brakes at the same time, the front right disk is 2.5mm thinner than the left and the pads about the same, I'm going to have to replace them all pretty soon. Total cost for repair was £400 including parts and service and the guys over at HWM, especially Vinny, were great. I'm still astonished by a design feature that allows this, I used to do avionics, a single signal that can drive such a behaviour is just mad, welcome to drive by wire.
Who'd have thought it, a perfectly good Alfa with electrical problems
Hope this helps someone else along the way, Bruce