Conflict with Office 2010 and Thunderbird ??

I am using Win 7 64 bit version.

 

Yersterday,  when I tried to save my files with Word 2010, I kept encountering an error: 

 

"Word cannot complete the save due to a file permission error"

 

I used the whole day to try to fix this problem and finally found the Word works well if I disable the Norton "Antivirus Auto-protect". So, my temporary solution is adding my working directory, including the Word files, into the "Items to exclude from auto-protect ", which solved all problems.

 

Today, another problem appears. I just found I cannot send email through Thunderbird becasue:

 

"Unable to open the temporary file. Check your 'Temporary Directory' setting"

 

In this time, I directly turn off the Norton auto-protect and my email was send out correctly!

 

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These experience are very frustrating. I have used Norton's NIS and 360 for 6 years and didn't realize the so called "auto-protect" could have so many bugs. Could you please help me to solve them as soon as possible? Thanks!