I spoke to an Alfa techie today and he said something interesting.
" to reset the ecu - switch the car on twice within 5 seconds, wait 30 sec and switch on again. the ECU will have resetted itself"
Has anybody heard of this before?
As Wrinx says, I've only heard to disconnect the battery for about 30mins.
Even the Haynes manual for my wifes old Cinquecento said to do this. The car may idle badly for a few minutes while the ECU relearns its stuff.