Thunderbird may not have closed properly for some unknown reason leaving a 'parent.lock' file in the profile. This may explain the 'need to close' error message.

Try this: make hidden files and foldrs visible:

• http://kb.mozillazine.org/Show_hidden_files_and_folders

Locate your profile folder:

• C:\Documents and Settings\<Windows user name>\Application Data\Thunderbird\Profiles\<Profile name>

The typical 'Profile name' may be 'xxxxxxxx.default', where the x's are letters and numbers.

In the 'Profile name' folder: If there is a 'parent.lock file, Delete the 'parent.lock' file.

You could also remove the Mozilla Thunderbird program before installing the a newer one. It is located here: C:\Program Files\Mozilla Thunderbird\ so you could delete that folder or use the 'Control Panel > Programs and Features method to uninstall.

System requirements for XP users. Depending upon your system requirements, you could use any version up to and including version 52.0

Version 10

• http://website-archive.mozilla.org/www.mozilla.org/thunderbird_releasenotes/en-US/thunderbird/10.0/system-requirements/

Version 45.0 needs SP2

• https://www.mozilla.org/en-US/thunderbird/45.0/system-requirements/

Version 52.0 needs SP3 Note that Thunderbird 52 is the last release to support Windows XP, Windows Server 2003, Windows Server 2003 R2, Windows 2008 and Windows Vista.

• https://www.mozilla.org/en-US/thunderbird/52.0/system-requirements/

This link will take you to previous releases.

• http://ftp.mozilla.org/pub/thunderbird/releases/

select the version. then select 'win32' then choose the language eg: en-GB is English British. Download the file. run file to install.

ReneJacques responded as a new thread instead of a reply https://support.mozilla.org/en-US/questions/1157534

Followed instructions to erase parent.lock but XP won't do it since it is in use, Is there a program that I can download to force it to be erased? Tried down loading a newer version but it too didn't show up on the screen. Otherwise other computer seems to be functioning OK.

re :stumped since old program does show as running in task mgr. If you open Task Manager and old program is running. select Mozilla Thunderbird and click on 'End Task'.

This should remove the parent.lock file, but if not then do it manually.

Have you tried to delete the program, so you do not have the program installed? remove the Mozilla Thunderbird program. It is located here: C:\Program Files\Mozilla Thunderbird\ so you could delete that folder directly or use the 'Control Panel > Programs and Features method to uninstall.

Then remove the 'parent.lock' file. then download and install fresh version of thunderbird.