Allen .. You are running 10.7.4 on a 12 Core Mac Pro?
After 25+ hard resets directly after the 10.7.4 update .. two days of no progress .. and no clue within the Activity Monitor .. or choice of application. I can't get to scan logs the Console before it freezes.
A bare bones clean install still provided no solution .. so what remains as the cause is the 10.7.4 update .. as well as the many others reporting problems. .. or my whole machine is shot. The SSD startup doisk has been checked .. and everything was working .. other than performance problems in Adobe Master Suite 5.5 .. and a common Quicktime problem.
Do you have a 12 Core 2.93 GHZ ... or another model?
What type of graphics card?
If you are using a PC nVidia GeForce Graphics card on a MacPro, update 10.7.4 causes black screen on restart.
If it is your case, try restarting using only the original Apple graphics card of your system, install 10.7.4 drivers (available on nVidia website) and restart again with your GeForce card.
It was exactly my case, and it works.
After updating Lion and reinstaling nVidia drivers, my GeForce GTX 550 Xi runs slightly 7% faster than before.
I have an 8, not 12 core Mac Pro, and am experiencing similar problems. I have an upgrade ATI card as well.
I tried taking my upgrade card out
I've tried reinstalling Lion, but it automatically installs 10.7.4.
I tried formatting and reinstalling Lion, but again it does 10.7.4 automatically.
I ran the extended hardware diagnostics program but it found nothing
I tried to restore 10.7.3 from a time machine backup but it freezes after an hour doing that.
Next I'm going to take my upgrade card out and try to restore a 10.7.3 from time machine
I was actually running 10.7.4 for a week before I started to have problems so I'm. It absolutely convinced it is a 1 to 1 relationship.
EDIT: I was actually running 10.7.4 for a week before I started to have problems so I'm not absolutely convinced it is a 1 to 1 relationship.
It still freezes when restoring from Time Machine even with the upgrade card removed.
Now I've put the card back in, and am installing 10.5.x as that is what came with the machine. From there I'll upgrade to 10.6.x and then I'll see if I can somehow go to 10.7.3. If I can't, I'll stay at 10.6.x; asuming I'm able to install that.
Because it freezes doing restore with any new hardware removed I'm not confident it will.