MacBook Pro freezing with flickering screen
My trusty MacBook Pro (MacBookPro4,1) has suddenly started freezing. It seems do it at random times, when I am not doing anything which should be particularly taxing (eg it often freezes when I am sitting reading a web page, and the computer is basically doing nothing).
The symptoms are as follows :
The computer is behaving normally, and then at a seemingly random moment, the screen suddenly starts flickering very rapidly. Sometimes it also has areas with patterns of black, grey, or white squares, each square being about 4x4 pixels.
The computer also freezes completely - except that the pointer will still move, which seems a little odd.
The computer does not react to anything I do except to move the pointer when I move my finger across the trackpad. The pointer moves much faster than usual.
Sometimes, if I wait long enough, the screen will stop flickering, and sometimes the pointer speed will return to normal. But the computer never unfreezes.
Looking at the Console, I see that there is a continuous stream of error messages from com.apple.launchd.peruser.501[277] - three error messages repeating over and over, the whole time the computer is on.
Message 1 : +(org.freedesktop.dbus-session[413]) posix_spawn("/opt/local/bin/dbus-daemon", ...): No such file or directory+
Message 2 : +(org.freedesktop.dbus-session[413]) Exited with exit code: 1+
Message 3 : +(org.freedesktop.dbus-session) Throttling respawn: Will start in 10 seconds+
I have no idea whether these errors are relevant to the freezing/flickering problem, nor whether they were already happening before the problem started to occur three days ago.
The following points may also be worth noting:
* I am running my MBP from a Kensington 12V power supply rather than the Apple 240V brick. But it has been working fine from the Kensington supply for a couple of years now...
* I upgraded the memory when I first bought the machine. IIRC, it is Crucial RAM.
* The freeze has always occurred while Firefox has been open. But that is probably because I always have Firefox open...
Can anyone shed any light on this problem?
MacBook Pro, Mac OS X (10.6.4), MacBookPro4,1