Thanks for your suggestion Brundle. The smooth screen fonts setting was set to "normal" rather than "cleartype". I unclicked it all the same, but it has not made a difference to teh fonts being blurred.
To clarify when I experience this problem - it is not when viewing web pages, but on emails taht I have been sent which have been created in HTML rather than in plain text. If I set my outlook to send in HTML, them my outgoing emails are blurred. If I set it to plain text then my outgoing emails are clear and normal. However, incoming emails are now always blurred if the sender sent them in HTML
Any more ideas? This happened since IE7 was downloaded as an aoutomatic update (wish I had not done that now)