This will not automatically resolve your problems but let me point out two frequent cases where the computer becomes unresponsive. I am a general interest computer geek (and it's been going for too long). So:
[1] Computer becomes unresponsive due to hard drive issues. The system will halt, waiting to hear from the hard drive, but no data is arriving. You're not getting a grey screen because no error has been reported back. The issue with hard drive controllers on OSX is a tricky one, anyone within the osx86 community will tell you. REASONS: chipset issues; incompatibility with kernel extension; bad cable; bad sectors.
and
[2] WindowServer (the graphics environment) becomes unresponsive due to graphics issues. The mouse cursor will move but the system is now out of the user's control. Logging in via SSH works but you cannot shut down WindowServer, and you cannot restart the machine since it will wait for WS to shut down. REASON: graphics adapter faulty, memory corruption, or software issues (osx).
*
notes to 1: It is reasonable to expect that the timeout priority is with the hard drive which might be experiencing anything from thermal recalibration to shifting of data from bad sectors (typically a very slow process). An additional priority may be placed on the filesystem which may decide at some point that it needs data relocated due to lack of free continuous space.
notes to 2: For some reason I have never been able to just terminate that process. If anyone with more knowledge has the details about this, please chime in.
For further consideration, mind that the mouse pointer redrawing is all hardware (99% sure of this). Additionally, *x networking has sufficient priority to give you ability to log in remotely via SSH or telnet (but I'd expect that to require some hard drive activity to call the demon in question).
Some people have reported that disabling graphics switching (it is possible!) has fixed their problem. And having written all this, my bet is a combination of the above. If i'm not getting this wrong, graphics switching is about negotiating an alternative screen buffer with the built-in chipset. On the i5 MBP the intel chipset handles both graphics and disk. So not a hard drive issue, but an issue where switching from one graphics chip to the other interferes with the hard drive (quite possibly the controller spits out something the drive wouldn't understand and erroneously would try to handle). This can be resolved by replacing the drive with one that has newer firmware. Which in turn may well be the reason everyone is confused about whether it is caused by drive X or Y or something else.
Add salt to your liking.
I'm crossposting this into the other freeze topic.