This is not the same problem as you are talking about the TOC whereas the RH8 problem is about the Project Manager. Also the cause of that cannot apply to RH7. I have therefore created a separate thread and slightly amended your post. The file concerned is the HHC, not the HCC.
I am not sure what is causing this so try creating a new TOC selecting the old TOC to copy from. I am hoping that will rewrite the TOC without whatever error is causing this.
Has anyone else reading this experienced the same?
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Thanks for responding. Not sure whether it is the same problem but it does sound similar. The files are no longer visible in the RH Project Manager pane and the TOC is populated with red cross icons.