Problem solved - I think.

Got absolutely no help from ESET Smart Security - they just insisted it was nothing to do with them and told me to call out a computer engineer! They have just lost a customer!

I e-mailed all the companies that I pay for virus/ malware etc. protection and firewall, none have yet responded.

I managed to find my way on to google product forums and sent them the same message yesterday. Closing down my computer for the day I noticed that MS wanted to apply 25 updates, just so pleased it was at the end of the day and not during the day!

This morning I read a message with instructions from google forums and carried out their suggestions as best I could. At then end of their instructions was a suggestion that I try a different browser so I closed Firefox and opened up Explorer then went to Gmail to look at the e-mails that were giving me the problem. Hey presto problems solved! I then shut down Explorer and opened Firefox went into Outlook to open up the same e-mails - No problems everything back to where it was a week or two earlier. Thanks google forums

Now in truth I do not know whether it was the advice from google forums or the updates from Microsoft that solved my problems but the fact remains that they are sorted so thanks to whichever company solved the problem for me.