"Some MacBooks may have left the factory with a thin piece of clear plastic covering the rear vent," Apple has admitted after some consumers who bought its latest laptop complained the Intel Core Duo-based machines were running too hot.

In a support document posted last week, the Mac maker said the plastic strip - discovered by MacBook buyers who disassembled their notebooks to investigate the problem - was "used in the factory to prevent dust" from entering newly manufactured machines. Symptons include not only overly warm laptops but constant fan operation.

Apple's solution: "If your MacBook has the plastic still over the vent, simply remove and discard it."

As yet there's no similar pointer to the MacBook Pro's heat problems, which some users claim is caused by too much thermal paste. Others reckon the paste has nothing to do with it. Certainly, the aluminium-clad notebooks have always been hotter to the touch than other latops, right back into the PowerBook G4 era. ®