I have been trying to convert a simple .odt text file to .doc, however it doe not convert properly, and the point 12 font came up to a ginormous size throughout the entire document!
Also, can you upload a small examople file here for someone to have a look at. By "convert" I assume you mean File > Save As ..., and you choose .doc. It is best to choose 97/2000/XP as it is the "least old" version.
Be advised that the grammar checkers are of questionable utility at best. Try that from http://www.languagetool.org
Edit: You can decide quickly if the enlarged text is a result of the conversion or of the document zoom. Place the cursor in a section of the affected text. The formatting bar will show the point size. If that is 12 pts, then the problem is the document zoom. If it is a greatly larger number, then the conversion is at fault.
Rory - I downloaded the language tool yesterday, and it is on my desktop - but it is not doing anything on my open office word pages!
Last time I was using it, before it disappeared due to computer troubles, it was good, and underlined errors.
You need a 32 bit version of the appropriate Java (see languagetool page for info) installed and selected in OO's /Tools /options /OpenOffice /Java. You will need to download this by hand from http://www.java/com; 32 bit versions have 586 in their filename. You also need to double click the languagetool .oxt file to cause it to install.
When you arrive at java.com, click the Download link, and then the FAQ about 64-bit Java for Windows as below. You probably run 64 bit Windows, so you get 64 bit Java by default; but you also need 32 bit Java, as well, for OpenOffice.
Your PDF file is being opened most probably in Writer. It should be opened using Adobe Reader and you need to set a file association to tell the operating system to use Adobe Reader to open such PDF files