With the latest Windows updates (KB2982791, KB2970228) Delphi 8-2010 can’t be started twice without a reboot because the IDE wants to create the file %TEMP%\EditorLineEnds.ttr that is now locked by the system.
The IDE extracts a FONT-resource to %TEMP%\EditorLineEnds.ttr and then loads it with AddFontResource(). The IDE’s finalization code unloads the font. But with the newest Windows Updates, Microsoft prevents the RemoveFontResource() function from unlocking the file (for security reasons). If you start a second IDE the resource-extraction fails and throws an exception causing the IDE to terminate.
If you have IDEFixPack newer than 2.7 already installed, you are not affected because IDEFixPack prevents the IDE from calling AddFontResource (this was a patch to work around a performance nightmare with an installed Adobe Type Manager). Thus the file is never locked.
If you are a new user to IDEFixPack, you may need to reboot after installing IDEFixPack if the font file is already locked.
IDEFixPack for 2006/2007 (if you have Windows 8 you need to use version 4.3 instead of 4.4)