Fiona, not sure exactly what is happening here, but you might find some useful info here:
http://www.adobe.com/support/products/acrreader.htmlCan you download any PDF's or do you always get that error? If so, you could simply trash all your existing Acrobat Reader files and reinstall, following the directions at the link above. BTW, the link you provided has a comma in it (just before the "pdf") which should be a period. However, assuming that you are clicking on the link on the maintenance page at MacInstruct, rather than trying to hand enter the URL, this is probably unrelated to the issue at hand.
Also, do you have the most recent version of Acrobat Reader? I've run into a few situations with people who didn't have the most recent version encountering errors, if the PDF was generated by the most recent version of Acrobat (full version). The most recent version of Reader is 5.05.
As to AppleWorks - it tends to install itself OUTSIDE the Applications folder for some unknown reason - are you sure it's not there? Did you have it before or have you never had it? Have you looked for it with Sherlock? Do you have the original install disks for the iMac? (though given its age, it may have a pre-Appleworks 6 version).
