After profiling a web application hosted in IIS, IIS may stop working altogether, even when not profiling, usually resulting in a page claiming "Server Application Unavailable" when accessed by a web browser.

A change was introduced in version 4.3 of the performance profile that can permanently affect the state of Internet Information Services when the web application needs to write files to a temporary directory. If the profiler exits badly (like it crashes or you close it in task manager), the broken configuration remains. This will be addressed in a future version, but for now, there is a fix that should get IIS working properly again:

• Run the Windows Registry Editor (regedit.exe)
• Navigate to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W3SVC
• Delete the value called "Environment"