First, I want to thank everyone for all of the feedback you've provided on this forum. While we're not able to reply to everyone, we are trying to fix the issues you're reporting. Yesterday we published some fixes to some common issues raised on this forum.
-Add incompatibility message when Visual Studio RTM is installed. SQL Express cannot be installed when Visual Studio RTM is on the machine. Previously there was a failure at the end of the install, now you should be alerted immediately if this is the case.
-Better direction to logs. There are a number of reasons an installation can fail and we often need the log files to help diagnose what went wrong. We have now linked up the final "View Log" link to the SQL Express logs that will help us most easily diagnose the issue.
-Address the continuous reboot. We've seen several people post that Web PI keeps prompting for a reboot. This should no longer happen.
-Added support for PowerShell 2.0. SQL Express can install with either PowerShell 1.0 or PowerShell 2.0. For people who had PowerShell 2.0 the installation would fail when it shouldn't. This issue is now addressed.
Thanks again and please keep posting feedback, issues, and suggestions. They help us track down the issues and we are listening!
Crystal