have you tried disabling your anti virus email scanner?

Yes and also smart firewall. I have not disabled Norton completly

The next stept to diagnose problems with Thunderbird, try the following:

• Restart Thunderbird with add-ons disabled (Thunderbird Safe Mode). On the Help menu, click on "Restart with Add-ons Disabled". If Thunderbird works like normal, there is an Add-on or Theme interfering with normal operations. You will need to re-enable add-ons one at a time until you locate the offender.
• Restart the operating system in safe mode with Networking. This loads only the very basics needed to start your computer while enabling an Internet connection. Click on your operating system for instructions on how to start in safe mode: Windows 8, Windows 7, Windows Vista, Windows XP, OSX

If safe mode for the operating system fixes the issue, there's other software in your computer that's causing problems. Possibilities include but not limited to: AV scanning, virus/malware, background downloads such as program updates.

My computer will not come up with the Safe mode window, its just comes up with drive options. I have restarted with add-ons disabled but it makes no difference.

try holding the left shift key while windows starts. from the fist sign of life on the machine.

I finally got to the safe mode and followed your instructions but nothing happened. I checked with the Thunderbird, set up new address, said no and the system confirms that the email address is there and that the password is correct

re : Norton

Example: I use Norton Anti-Virus/Firewall. Sometimes, after an update, Norton still thinks it can allow only the previous version - not that it shows what version it is using. I then have to close Thunderbird and access Norton. Settings > Network > Smart Firewall > Program Rules Locate Thunderbird and set to 'Allow' On occasions, I have had to set to 'block', ok and then reset to 'Allow' and then OK.

then open Thunderbird.

I have tried this and still Thunderbird will not open. It goes to connect but does not seem to be able to access the pop.3.co.nz (xtra) web mail box which is yahoo mail nz

I'm not sure you have the correct server settings.

Are you a Spark customer ? If yes, look at info under heading 'Pop Mail email settings with SSL' http://www.spark.co.nz/help/internet-email/getstarted/how-to-set-up-xtra-email-for-the-first-time/

All setting set correctly but I have since tried Eudora 7 which is similar to Thunderbird and it replied "Permission Denied Error 10013"

Are you a Spark customer using Yahoo Xtra email?

You said pop.3.co.nz this is not correct, so please post the requested information to make sure the forum knows exactly what Thunderbird is attempting to use.

In thunderbird Help > Troubleshooting Information Click on 'copy text to clipboard' paste info into this question. you can remove all info on fonts and printers but nothing else.

Typo error sorry. To Matt and Toad-Hall, A young friend came on to my computer through TeamViewer and checked out my setup and seems to have found the problem in my Profile folder which was corrupt and has managed to get Thunderbird working again. He is going to go through my old Profile and clean it so that we can reload the inbox folders. I want to thank you both for your help in trying to trouble shoot my problem. I appreciate your efforts as after trying Windows Live Mail I can't wait to get back to the layout of Thunderbird.

Regards to you both

Doug

Tell your young friend to use this add-on... it makes importing from an old profile much easier. https://addons.mozilla.org/en-US/thunderbird/addon/importexporttools/