I often have emails etc., where, instead of illustrations, there are blank panels with a red "x" the top left corner, which, when I click, has no result, do I have to have a certain installation so that I can view these?

These x's are the result of your email-program's settings or could be caused by your AntiVirus program stripping any attachments.

Let us know what emailer you use, we can then guide you in the right direction.

I use Outlook Express,I'm pretty sure that the same occurred before I installed NORMAN AV,.....hope this helps.

Check under Tools/Message Rules/Mail if you have any rules concerning attachments.
If there are any there that block attachments from viewing/loading etc. you can easily change those.

Another place to look for them, and the mostlikely candidate, is under Tools/Options/Security.
There is probably a tick-mark where it says: Do not allow attachments....
Unticking this should make your pictures etc. visible (but only next time, after you change this and download your next email with attachments. It won't allow you to see the stuff attached to current or older emails [they were suppressed]).