Right ho. The situation has been resolved but I will tell you how it happend for future reference.
In the process of cleaning up my computer I deleted Winfax Pro, which I now believe was causing the original problem. I deleted Winfax Pro as part of geting anything assosiated wtih Norton and symantec off my system. After I had done all this and I started outlook A box came up saying: 'The add in DCCEXT32.DLL could not be installed or reloaded. This problem may be resolved by using Detect and Repair from the help menu.'
After this came up I thought I'd restart to seee if it would clear the problem - it didn't, but I noticed that I did not have that annoying screen coming up saying that it could not shutdown. Then I googled DCCEXT32.DLL and found the following site, followed its instructions, and bingo! All my outlook problems solved.
http://support.microsoft.com/kb/236136Hope this is a help for anyone with similar problems.