When I playback something that has been written in music notation, not all notes play. Why is this?
How do I change the tempo of the vertical bar during playback so that it stays in time with the music playing in the notation?

Check the "Prepare using nnn Millisecond Buffers" setting in Preferences > MIDI > Playback and Recording. Try doubling the default value of 250 to 500.

The problem is rooted in the sound card that came with the computer. Doing what scook suggested will sometimes help.... it gives the hardware more time to think or look ahead, but ultimately, the sound card from the factory is woefully inadequate to do what Cakewalk software asks it to do.
 
This problem as you describe it, is worse with midi based music. It takes more time and power to process midi than it does audio.
 
Better performance is obtained with a dedicated USB based, external music interface, running ASIO drivers.
 
Most of us here are using the external interface and would never consider going back.

Thanks for the advice.
 
The vertical cursor moves much too fast for composition, probably double speed. The note durations are correct but the cursor moves too fast. Any suggestions?

In midi, you can simply change the tempo to a much slower tempo. The "Now time line" indicator will move at the tempo on the project. This would allow more time to do whatever you need to do.... then when you finish, simply change the tempo back to the original tempo.
 
NOTE: this only works with pure 100% midi projects. If the project requires audio, DO NOT record the audio into the project at the slower tempo. Reset the tempo to the final tempo and then record the audio. Changing the tempo with audio will require realignment of the audio clips if you do change the tempo after recording them. Not impossible, but certainly a pain.

Not quite sure if I understand. When I playback some notation the vertical cursor moves probably double the speed of the music playback
 

marcushnz
Not quite sure if I understand. When I playback some notation the vertical cursor moves probably double the speed of the music playback

That's got nothing to do with tempo setting, I guess. Some kind of sync thing. I've never heard of such a problem. So the Now Time really reaches the end before the playback (and the view stops scrolling??!!) and the project still keeps playing to the end normally? If so, very weird.

It could very well be related to the sound card in the computer as I mentioned above.
 
In a laptop I used, I had a very jumpy "now time line" indicator on the larger projects. That was not due to the interface but to the computer being "stretched" to try to process the music...... a duo core intel with barely enough memory to keep everything running..... but it only happened on the really big and CPU heavy projects filled with synths.