It also sometimes tells me that I do not have permission to open this file and I have to contact the administrator (ie me). How do I get it to just make me an ordinary pdf file that can be opened and /or emailed without using the adobe email system which does not work anyway. The only option I see is to export as pdf and I have tried clicking and unclicking most of the options in that to see what works. Mostly I have no idea what it is I am clicking so I just try different things.
Welcome to Ask.LibreOffice! Please edit your question to include additional information: e.g, if you have problems exporting other Writer files to PDF, if your file is .odt or .doc or .docx, what e-mail application you use (Outlook? Thunderbird?). And please, consider changing your Windows Vista for something better!
I use google chrome for email and I am exporting odt files to pdf files that look like other pdf files I have from elsewhere. I can open them in adobe acrobat but can’t send them because I don’t have the sort of email that sends from my computer. I would consider changing vista- all I need is money -offers?
Maybe this is will help 
http://wiki.openoffice.org/wiki/Documentation/OOo3_User_Guides/Getting_Started/Exporting_to_PDF
That is open office, not Libre office. I got rid of Open Office because I couldn’t nail down illustrations reliably on a document no matter what setting and anchors I used. I’m not a programmer and I don’t always understand the technical language of the help pages.
Please check the LibreOffice Writer Guide, chapter 5 “Printing, Faxing, Exporting, and E-mailing”, which has a section dedicated to exporting to PDF.