I occasionally have tracks that "flat line" when I zoom in. IOW the normal waves turn to a line as if ther is nothing there but it plays normally and even shows the peaks etc.
Not all tracks do it.
The same tracks do it.
It makes it impossible to edit.
Is there some recognized thing or setting that is doing this?

Maybe you are zooming in a little too much?

Well the other tracks are fine so I doubt that.
The zoom starts fairly far out (like most of the song's length) so it is impossible to do any editing.

http://dl.dropbox.com/u/24683934/zoom.jpg
Here are three levels of Zoom in one picture.
Note it starts fairly far out but the other track gets in a bit more before "flatlining"
Again, this does not affect the sound, just the visual.
Sometimes it's ok & I can zoom rt in. But usually this is the result.

OK I see what you are seeing. The only thing I can suggest is try to empty your picture cache folder. You should find it in your Cakewalk Project folder.

I hope that fixes the problem. 

Try this when the problem occurs:
To redraw waveforms
1.
Select the clips that you want to redraw.

2.
Right-click a selected clip, and choose Associated Audio Files on the pop-up menu to open the Associated Audio Files dialog box.

3.
Click the Recompute Picture(s) button. A dialog box appears, asking if you want to recompute the pictures on the selected clips.

4.
Click OK.

Double post-Sorry
 

I tried both suggestions but no change, but thanks for the ideas.
Glenn

Glenn . . . how are you doing the zooming ? ALT-scroll middle mouse wheel or zoom-drag window with left mouse . . . and do you get the same result no matter how you zoom ?

Seems you have a similar system spec to me, but what graphics card do you have ?
I have never had this zoom problem.

Also, when you adjust the track zoom factor (drag on the vertical bar left to the waveform display), do you still get the "flatlining" ?

Thanks for helping on this
I use Alt /wheel usually but (Z) Zoom drag and track zoom do the same thing.

Graphic card is  NVidia Gforce 8500 GT 
version 301.42 
set to 1680 x1050 (native)
32 bit color.

Further info is that it seems related to the (same 2) waves only when they go behind the left side of the pane (the clip info)
Experimenting, I find I can keep most of the left side visible if I zoom at the very start keeping the left end of the track in view and then pan to the right. 
Then, as I pan to the right, at some point (first track at 23:04 and the next one at 29:02) they flatline.
But as you see in the image, the right side beyond 68 never goes away and the flatline always starts at that point and to the left.
It seems to be something to do with the info on the track up to that point.
One starts to disappear before the other.
If I clone the tracks they do the same thing.
I wonder if some edit process has done this.
Sigh, I'm thinking live with it or retake the two (fingerstyle guitar) tracks.

M_Glenn_M


Thanks for helping on this
I use Alt /wheel usually but (Z) Zoom drag and track zoom do the same thing.

Graphic card is  NVidia Gforce 8500 GT 
version 301.42 
set to 1680 x1050 (native)
32 bit color.

Further info is that it seems related to the (same 2) waves only when they go behind the left side of the pane (the clip info)
Experimenting, I find I can keep most of the left side visible if I zoom at the very start keeping the left end of the track in view and then pan to the right. 
Then, as I pan to the right, at some point (first track at 23:04 and the next one at 29:02) they flatline.
But as you see in the image, the right side beyond 68 never goes away and the flatline always starts at that point and to the left.
It seems to be something to do with the info on the track up to that point.
One starts to disappear before the other.
If I clone the tracks they do the same thing.
I wonder if some edit process has done this.
Sigh, I'm thinking live with it or retake the two (fingerstyle guitar) tracks.

Did you delete the data in the picture cache folder?