156 Strangeness

[Alfa_75_Steve]

Mrs 75 called me from the supermarket car park.

The 156 was playing up:

Temp gauge in the red (but car not overheated)
Speedo wouldn't go above 20mph (but going faster)
Selespeed wouldn't change in City mode and wouldn't change above 2nd in
manual mode

I got there, the ABS warning light was on, the ASR was off and the
self-check told me we had a VDC(?) failure.

Fortunately, I had grabbed my NetBook and AlfaDiag cable.

15 mins later, having cleared the fault codes, re-calibrated Selespeed
and reset the main ECU, all was fine again.

Stupidly, I didn't make a note of the fault code, though.

Any ideas what may have caused it?