The auto install/update functions are part of the core WordPress files. If your install/update fails there is nothing wrong with the plugin. Your server may be having trouble with resources such as low available memory or too high of a load demand. Or something random simply failed during the install/update. At this point, a manual uninstall / auto install might be the solution.
Sometimes the WordPress auto install or auto update function fails and the plugin is left in a state of non-functionality. In that case you will need to uninstall and reinstall it. First try a manual uninstall, then do the auto install. If the auto install is not working then try a manual install.
See this page for instructions
http://www.fastsecurecontactform.com/reinstall-wordpress-version
Thanks for taking the time to respond Mike – much appreciated.
Since writing the post, I tried a manual install and that all went according to plan. So, as you say there’s nothing wrong with the plugin.
I also took the matter up with my Hosting Company and they are currently rebuilding Litespeed as they say this could have caused an issue. I suspect that this is the main problem here.
The other point is that this is the first plugin I am updating since WordPress 3.5.2 was installed the other day. Don’t know if that has anything to do with it.
I’ll let you know! By the way, I use the plugin on all my sites, so keep up the good work!
Chris