Cannot complete this action. Please try again. SharePoint 2007 Default.aspx Problem

A user tried to access their site on a SharePoint 2007 server, but was unfortunately greated with the wonderful, unhelpful message of:

Cannot complete this action.  Please try again.

This error occurred when trying to access the default page of the site i.e.: http://Server/subsite/default.aspx

A quick search around the internet and it seems many people have had this same problem at some point, but no one could find a solution that wasn’t as drastic as deleting and creating the site, restoring the server or even trashing and rebuilding SharePoint!! On a live production system, this wasn’t practical and would require a bit of work to sort out!

I run one server which consists of a main site for my project, with sub sites for each team on that project.  The problem was occurring for just one team sub site.  With a little poking around, I found I could still navigate to all the sites content and its settings, via the parents Content and Structure options – (“Site Actions” –> “Manage Content and Structure”).

Using this navigation option, I went to the master page viewer and tried to upload the master.default page from my fail over server which was working perfectly.  This didn’t work and caused a new “File not Found” error when trying to view the home page of the site.  I restored the previous version to get back to square one.

With my only option looking to be to restore the subsite from the backup, I tried one last thing.  Within the Manage Content and Structure pages, I deleted the Default.aspx file from the problem site.  I then copied a default.aspx page from a known working sub site.

On refreshing the problem site, this solution worked fine and I was once again able to navigate to  the problem site with no errors.

I am still not sure why the original problem occurred, so if anyone has any ideas I would be most grateful.