Appears to me as a timing problem.  Sound card works in all applications except I can not playback longer than 1 second, even when using a device not requiring sound card.  Transport is part of the problem.  Any file will play about 1 second, then transport stops.  Play is normal using Nero player.
 
the problem arose when I removed then re-installed Sonar after installing a new graphics card.  No other problems on the computer that I can discover. I am able to record.  I am running Sonar on Windows XP service pack 3. 
 
I am at a dead end and need some advice.
 
Richard

I think it's the dropout detection that is in working.
 
Reselect ASIO and ins/outs and check...ASIO was never default as I remember.
 
Can you activate audio engine - there is a button in gui somewhere as I remember.
 
There are settings in AUD.INI though, if you increased those before.
You can set the amount of time for dropout to inflict and stop transport.

ASIO checked numerous times.  Audio engine activates.
 
I forgot to mention that when the playback stops (after 1 second) most menu items act as though the play was continuing, and I must rewind to start to be able to do anything, including exit.  I do not remember seeing any dropout message, and will check it again shortly when the system is available to me, and will then again check aud.ini.
 
Richard

Shot in the dark.... When you installed the new graphics card, any chance it installed a background utility (that's now interfering with the audio engine)?

I don't know how to check that, but I will try.
 
Richard

Have a look in Windows control panel/device manager for extra sound and game controllers or any hdmi audio interfaces. If any are found disable (but do not uninstall) them. While you're looking, check the audio interface you use is shown as working.

rjwayland
I don't know how to check that, but I will try.
 
Richard

START - Inside Run/command line box: type msconfig
Startup tab - uncheck any process related to graphics /monitoring.  OK out of window.
Reboot
 

Well, that scares me a bit.  I will have to ponder a bit on it.
 
Meanwhile, I have discovered that there are updates to Sonar 4, 4 total, and I have only the first.  I have downloaded them and will install them, even though it seems a waste, as Sonar has until now worked fine without them.
 
Richard

Whoopie ding dong!!
 
Thanks to all for their help.  It got me mucking around the right places and now I am able to get back to using Sonar, which has been good to me for years, starting with DOS version of Cakewalk 1 or maybe 2. 
 
Now I can relax and get some rest, which I really need, as this problem really stressed me.
 
I do not understand why the updates were absolutely necessary now, but that is the way it is.  It must be related to the new display, or, more likely, when the technician installed the new card, he had to move the audio card to a different slot, or remove it while he worked.  This installation is the sort of thing I have always done myself, but I am a bit concerned that age might be affecting the agility of my hands. 
 
Richard

Sonar 4 you say? It might be good for you to know that there's a major change between 4.0.2 and 4.0.3 in that 4.0.3 has a new audio engine and I found (as in it was my experience and not necessarily the same for everyone) 4.0.3 to require a higher latency setting to run the same project.
4.0.2 is/was much more efficient when it came to using PC resources.