Corrupted applicationHost.config file in IIS 7

IIS7 stores its parameters in an XML file, located typically at C:\Windows\System32\inetsrv\config\applicationHost.config. This is a nice solution as every parameter is clearly readable. Unfortunately, there are still some bugs (maybe in IIS 7, but some problems with anti virus programs have also been reported) and this file may be corrupted.
What to do when this file is truncated? Reset it and loose all of your settings?
Luckily IIS makes a backup each time you make a change. All those versions are stored in the folder C:\inetpub\history\. All you have to do is to copy a former applicationHost.config file into the C:\Windows\System32\inetsrv\config\ working directory.