I set up a loop, like I normally do, and started recording takes.  After about 5 or 6 takes, SONAR suddenly freezes.  I can't break out.  I can't do ctr, alt, del to bring up task manager.  The PC is just hung...keyboard and mouse not responding.  I finally hold in the power button and the PC shuts down.  I restart the PC and SONAR, load the project and start recording again.  After about 5 or 6 takes I get the same issue. 
 
What do you guys suggest?
 
Additional note, I started a backup of the projects just in case.  The backup is running without issues...the PC is running fine.  I'm backing up about 131GB.  It's about 1/2 way done ... 55 mins. remaining.  This really does look like a SONAR or project issues.  I have NOT installed any new plugs since I started this project so I don't think its a plug causing the problem.

So if I am reading this right, you are backing up the same project that you are recording? Did I get that right?

I wouldn't backup anything while trying to record.

[edit]

I re- read your post. Sorry for my misunderstanding.

What are your audio interface buffers set to? Are you using ASIO drivers?

Hi
The first thing I would do is update your interface to the latest driver and firmware. I might be look at updating other drivers as well... If that does not resolve it try running Sonar in safe mode to see if a plugin is the issue.

Is it just one project or all of them?

I appreciate the suggestions so far, however, this is a "static" dedicated system that is not on any network.  I've been recording with this setup for a few years now.  In the last year I have not installed any software, updates or plugs.  The system was working fine last week and just started having an issue today.  I haven't changed any of the settings or installed anything.  I don't see how a driver would suddenly start causing a problem without an update or change being made.

amiller
In the last year I have not installed any software, updates or plugs.  The system was working fine last week and just started having an issue today.  I haven't changed any of the settings or installed anything.

Do you do Windows update?

Can you please detail the characteristics of the project in question?  I am thinking the logical place to start looking is with potential issues with 3rd-party plugins, particularly those that are 32-bit.
 
Can you please try doing a quick test?  I would like to see if the problems happen if you load it in Sonar's Safe Mode and skip the loading of all the plugins (when you open in safe mode it asks you if you want to open each plugin, just skip each one), then do some dummy recording takes to see if you are then able to get past 6-7 takes.  In any case, exit without saving, after the test.
 
Could you also please list all the currently loaded plugins that are in this project?  Both synths and effects, please.  I could then do some quick research on them to see if anything turns up.
 
Here is the link to the Sonar doc for opening a project in Safe Mode.
 
http://www.cakewalk.com/Documentation?product=SONAR%20X3&language=3&help=Dialogs2.094.html
 
Thanks, 
 
Bob Bone
 

Something has either changed or Sonar/windows is being put in a different scenario from the norm (e.g. windows update which has altered a dependancy), project got corrupted or you or your PC is doing something different (like a plugin in a different scenario in a particular project, or something is triggering a bug with an existing driver).

Is it one project or all of them?

Cheers..

Sounds like the OP is behind on running at least Windows Update, if he has not connected to the web in one or more years.  Drivers may also be behind the times, and even possible firmware.
 
To the original poster:  It is quite possible that something is far enough behind in maintenance that you have started to have issues from X3e expecting a more current system.  This has been the case with some C++ routines from Microsoft being out of date, for some other folks in the forum in prior threads.
 
I recommend you consider getting your Windows up to current maintenance levels for whatever version you are running (7 or 8 or 8.1), and also checking to see if there are driver updates for things like video drivers or even your audio interface.
 
I was having some weird but bad problems a couple of months back, and it turned out I was behind with applying maintenance to my audio interface drivers.
 
Bob Bone
 

One thing that's not clear,, is this one project 131 GB or is that your whole Sonar Projects folder?? 

First thing I'd do is make a copy of the project... and load it sans any plugins.
Do you get the same crash when loop recording?
What happens if you start with a new/empty project... and work with the same type of loop recording?
If the problem persists in both these scenarios, I'd test the system's RAM (just to be sure).