For the second time in six weeks, Apple yesterday delivered a firmware fix designed to stop 27-in. iMac screens from flickering. Initial reports from users who installed the update were mixed, with more saying that the flickering continued than saying Apple's second try had resolved their iMac's flaky display.

"The 27-inch iMac Display Firmware Update 1.0 updates the display firmware on 27-inch iMac computers to address issues that may cause intermittent display flickering," Apple said in a curt description of the fix.

In late December, Apple released a 27-in. iMac graphics firmware upgrade that was also pitched as a fix for flickering. Most users that reported the results of that update, however, said that it had not solved their problems.

Somewhat the same reaction was evident this time, although only a handful of users had posted their findings on the enormous support thread dedicated to flickering screens. "The second firmware didn't help me either," reported "dxgriffiths" on the 1,600-message thread. "Still getting little dropouts and surges in brightness every few minutes."

"I just installed the update, as it was restarting I had 2x blackscreens happen, which had not happen[ed] on this machine only the occasional flicker," added "Leisas4" on the same thread an hour later. "Not a good sign."

Others, however, said that the update had done the job. "Firmware seems good to me," said "Bamtan".

Display issues have plagued Apple's 27-in. iMac desktop computers since the new machines debuted October 20. Users have reported cracked screens, a yellow tint to the display, black banding and, of course, the irritating flickers.

The 294KB firmware update can be downloaded from Apple's support site.