To avoid the error message KEY_XE.reg is missing during installation of Oracle Xe 11g on windows 7 64bit.
1. Start the installer ‘Setup.exe’ and click Next until asked about password.
2. Do not press next. Open with Windows Explorer the folder like this:
C:\Users\\AppData\Local\Temp{60712028-B7B0-4EC3-9C28-663111EC954A}
3. There will be a file OracleMTSRecoveryService.reg. Make a copy and rename the copy to KEY_XE.reg
the click Next..