I have just got last update, opened an older project, created c. Ipswich, five synths incl. two instances of SampleTank 3, Z3TA2, EZkeys, two instances of Lounge Lizard, no more than 6 effects incl Amplitube 3, generally no big deal, played with no problem in a past. Now the screen gets whited out every few minutes, just playing midi files, grrrrrrrrrrrrr. WTF ?

Afrodrum
I have just got last update, opened an older project, created c. Ipswich, five synths incl. two instances of SampleTank 3, Z3TA2, EZkeys, two instances of Lounge Lizard, no more than 6 effects incl Amplitube 3, generally no big deal, played with no problem in a past. Now the screen gets whited out every few minutes, just playing midi files, grrrrrrrrrrrrr. WTF ?

When it's working, Save As... under a different name. Then, open that project in safe mode without any plug-ins. See what happens. If the project is stable, try again any enable half the plug-ins. See if it's stable. If not, there may be a problem with one of those plugs. If so, try again and enable the other plug-ins.
 
Also be sure to check the IK site for any updates. I don't think they notify you when updates are available. 

You might start by rolling back to Manchester to confirm it's the update that precipitated the problem.

Anderton
When it's working, Save As... under a different name. Then, open that project in safe mode without any plug-ins. See what happens. If the project is stable, try again any enable half the plug-ins. See if it's stable. If not, there may be a problem with one of those plugs. If so, try again and enable the other plug-ins.
 
Also be sure to check the IK site for any updates. I don't think they notify you when updates are available. 

 
Seven more crashes since the post, unbelievable. This project without plugins will not play anything, it is just seven tracks with six synths and midi clips on them, four synth active and one yet empty audio track. My IK is as recent as it can be. I will try to roll back as Brundlefly suggested.

Crahes in Lexington too but a lot less frequently. Sample Tank is a suspect, I went back to latest update, freezed one instance of SampleTank 3, 10 minutes on - no crash.

Can you post a link to one of your crash dump files? 

Noel Borthwick [Cakewalk]
Can you post a link to one of your crash dump files? 

Sure, tell me where to find it please.

If there is a crash SONAR will save a minidump in this folder - type that into windows explorer:
%APPDATA%\Cakewalk\SONAR Platinum\MiniDumps
 
If its a crash in SONAR it will be in the root folder. If its a plugin crash it will be inside the Plugins folder.
You should be able to find the file based on the timestamps of when the crash occured.

I found folder it has lots of old crashes and none of the recent. The newest dmp file is from January even though I had plenty of crashes in the meantime. This is an odd one, all of a sudden transport stops, "Sonar not responding" message and buzz noise volume of which depends on last HW outputs level. Buzz remains even when Sonar window is closed. The only way to kill it is to restart computer.
 
    btw, the project with frozen Sample Tank track crashed eventually after 15 minutes of looping.

If there are no dumps it's likely that you are hanging the app and not crashing.
A hang and a crash are completely different things.
Are you using any 32 bit plugins?
It's very unlikely to be related to the newburyport update.