After I attempt to install any component, particularly my mtwMigrator component, I get the following error:

    * Warning! Failed to move file.

This really is on the fresh install, with FTP Layer switched off, with default content installed, Joomla 1.5.14, latest PHP and my_SQL versions, Legacy mode switched on.

One such reason for this error is because of file permissions. Joomla must have the ability to copy the files out of your component in to the components and administrator/components sites. When the system user the webserver runs as doesn't have write permissions to those folders, it won't have the ability to copy the files over.

The FTP layer can there be to obtain for this problem. Using the FTP layer on, you upload the aspect of the server first, then its FTP'ed in the temporary directory to localhost. With this to operate, the FTP user you specify should have permission to create towards the components and administrator/components folders.

Normally, all directerories must have 755 (rwxr-xr-x) and all sorts of files 644 (rw-r--r--). If you wish to set probably the most sites not to-writetable, you'll need a minimum of the sites indexed by Help > System info > Directory Permissions. (Here you may also check which sites have to be transformed, as non-writetable sites are proven in red-colored.)

In certain hosting that is shared conditions, 755 / 644 is not enough, as who owns the file isn't the (Web)Server User, however the FTP-User ... so either change it out to 777 / 666 (not suggested, while you allow others to create your files), or get the FTP layer to operate.

Another try: Joomla! doesn't work yet using the recent PHP 5.3. Do you need PHP 5.2? (Similar Problem in the Joomla Forum)

I'd an identical problem when moving between machines (I understand you stated it had been a brand new install - but someone will dsicover this useful). Make sure the $tmp_path entry in joomlaconfiguration.php is pointing to some valid directory. Mine wasn't.