The standard electronics used by every team, and supplied by McLaren subsidiary MES according to a FIA tender contract that was recently extended, was also toying with the patience of engineers up and down pitlane as the 'middle' pre-season test in sunny Spain got into gear.
Red Bull - not McLaren's closest friends in the paddock - were being the most vocal at the Circuit de Catalunya, saying the new software supplied by the McLaren company was causing frustration.
"But I don't think we were alone in that," said race engineering chief Andy Damerum.
According to Auto Motor und Sport, the problem was so devastating that many teams were operating their cars completely blindly.
"It was like the Middle Ages of motor sports," said the German publication.
The background to the glitches is that McLaren has updated its software for the electronic control units - the 'brain' of the F1 cars - in preparation for the turbo V6 rules of 2014.
With energy recovery 'ERS' systems to play a much bigger role next year and beyond, more will be asked of the standard electronics and "We have a year to eliminate any weak points", an FIA source said.
Early on in Barcelona this week, however, the new electronics utterly failed.
"We could not talk to our car," confirmed Williams' veteran team manager Dickie Stanford.
Because the problems were so widespread, and data so crucial for F1 testing, MES had to revert to the 2012 software, and is now steadily updating the teams with the de-bugged versions.
"Every day there are new upgrades," said Ferrari's engine boss Luca Marmorini.
"We are sure that everything will work properly in Melbourne."