I too have been having this problem, in addition I was unable to install the IE7 upgrade. The error message given by the upgrade was to look at certain registry entries. Even though I am the administrator I received a error when I tried to open the registry entries listed as well as some of the other registry entries. I realized that I did not have the right permissions to open the files. I searched the we until I found this web site
Aaron Stebner's WebLog : Solving setup errors by using the SubInACL tool to repair file and registry permissions
in here Aaron Stebner describes how to restore permission to the registry for the administrator. I tried it and it worked, I was able to install IE7 and the Quick Launch stays active. I did a Google search on SubInACL and registry permissions which resulted in more examples of how to fix the registry problems. I hope this helps you as much as it did me.