Some pdfs opens and others, when opened, causes a problem with the software and it gives an error saying that it has stopped working and then closes. Any ideas? These are not protected files as far as I can see.
Don't have an answer as to why it will open some pdfs and not others, but I found a way of working around it:
Open the pdf in Adobe reader (or whatever reader is avail), then print to pdf24, save as new file, and wow! pdf24 will open it and now u can delete and add pages to your heart's content!