This looks like an issue with a particular graphics driver and OpenGL usage in Blender. If the issue is really fixed in 10.7 that indicates a bug in the apple drivers, for which we might find a workaround, but first we'd need to be able to redo it our find out more information about what happens here. I've been using Blender on a MacBook Pro with Nvidia 9600M GT on 10.6 and 10.7 now and have not seen this issue before.

How often does this freezing happen? Does only Blender freeze or does the entire system freeze?

Also the issue reported for Windows in this thread is probably unrelated, bmesh was added only in 2.63.

The freeze happens constantly, Every few minutes.
The freezes seem to be system wide in that I can't command-tab to other applications.
'm testing the official 10.6 and 10.5 builds.
Tried setting Compute Device to None, CUDA and OpenCL as well as toggling VBOs in the preferences with no effect.

I much prefer staying on 10.6 and am actively avoiding 10.7. I am currently on 10.6.7. Could try 10.6.8 to see.

I believe this also happens on my laptop (though it's not in front of me to confirm).
"Core 2 Duo" 2.2 15-Inch, 2.4 GHz "Core 2 Duo" processor, 4Gb Ram, NVIDIA GeForce 8600M GT 128 MB of GDDR3 SDRAM

Ok, if you can't tab to other windows it at least confirms it's a driver bug, not Blender itself locking up. This type of issue is nearly impossible to debug without us having access to such a machine that has this problem. If we can pinpoint which exact change broke this, it might be possible to work around the driver bug.

There is also a way to run Blender in software OpenGL mode, if you run this command from the console:
BLENDER_SOFTWAREGL=1 /Applications/blender.app/Contents/MacOS/blender

I have the same problem and could also provide information about my system, if that helps.
I'm working on 10.6.8 and for me, this problem has been around for a few Blender versions, too.

Other system specs are almost identical to Zef Fiolas:
2x2.26Ghz Quad-Core Intel Xeon, 16 GB RAM, NVIDIA GeForce GT 120: 512 Mb VRAM

I have a feeling that the problems do NOT occur when viewport shading is set to wireframe.
In the user preferences I have also tried to change the window draw method, the problem still occurs.

And, it's definitely the entire system being frozen, since the clock in my menu bar stops counting up seconds for a short while.

Please let me know if I can provide further information to track down the problem.
Unfortunately, I cannot drag my computer all the way to Amsterdam. ;)

Moved from Blender 2.6 Bug Tracker to OpenGL errors

This is an OpenGL issue which is really difficult to resolve if developer doesn't have access to a machine on which bug happens. Will move to OpenGL tracker and hopefully somebody from a community develoeprs will manage to reproduce and fix it.

The problem is most evident when selecting vertices in brush mode (c - key). There is a freeze after each few vertices selected.
The box select mode to select vertices (b - key) behaves normally.

The freezing is also happening in Mesh and Textured mode but when in Mesh mode, things seem ok.

Running the command BLENDER_SOFTWAREGL=1 /Applications/blender.app/Contents/MacOS/blender definitely helped with this issue.

"The freezing is also happening in Mesh and Textured mode but when in Mesh mode, things seem ok."

What do you mean? You wrote Mesh mode twice, do you mean solid and wireframe?

Recently it even happened to me in wireframe mode, so what I said above is not correct, actually.


Also (this might be a really stupid question, forgive me, I'm not a developer):
Would you guys to debug this actually need physical access to the machine? Or would it be sufficient to let someone of you have remote access via internet to an affected machine (I have NO idea if or how that would even work). If the latter is possible and you guys are willing to have a look at this, I could probably offer that you have a remote look at my machine.

As I said, just a suggestion, might be totally stupid. ;)