Thanks for all the help. I've just now tried one document as an example. It's a Notepad doc. I tried to open it in Notepad, Word, and Firefox. All three gave the gibberish. Looking at its 'properties' confirms that it's a Notepad doc. I'm a bit stumped.
Just to make this clear; when I plug in the USB stick, I then take the option of viewing the file (or folder or whatever) with the appropriate Windows option. A new window opens up, full of little shortcuts to the individual docs, be they Word (or Notepad) or music or pictures, all complete with names. I've also tried a music file and nothing at all happened after i told it to play/open.
Is it usually easy and straightforward to save bookmarks, pictures, music and Word/Notepad documents to a memory stick and then retrieve them later? I would have thought that the computer would automatically sort out any differences caused by newer versions of programmes. I need to save stuff coz my PC is 8years old (and wasn't exactly high spec then) and getting slower and might die one day soon.