The past few days I have been experiencing WIFI drops after waking up my 2011 iMac from sleep. When it happens, the iMac seems unable to "see" any WIFI networks, and the only remedy is to restart the Mac. I feel that it started happening after upgrading to the recent OSX 10.7.4 update a few days ago.
After several experiments the issue seems to disappear when disabling the Little Snitch network filter - nothing else seems to help. Do any of you guys have the same WIFI problem?