You need to open the Output view and see what (if any) errors are being encountered.
You may even need to create a new layout. Sometimes that works to resolve it. But it won't help if a topic is the culprit.
Thanks Rick. The only errors I can find in the Output view are as follows:
Compilation failed while compiling Version3.hhk.
Compilation failed while compiling ,,,.
Compilation failed while compiling ,0x0,0,0x520,[-1,-1,-1,-1],0x0,0x0,,0,0,0.
Compacting file system...
The following files were not compiled:
Does this shed any light on what/where the problem is? I tried deleting the HHK file and reopening and compiling but no change.
I also tried creating a new layout and now the chm is larger and does open but only shows the start page with no nav controls.
Can you help me any further?
The hhk file is your index. Do you have an index? The other error looks like it comes from the Window definition in your project. This would also explain the loss of nav pane, etc. I would try recreating your windows in the project settings.