According to Microsoft, if you remove FSX from the computer and then try to reinstall the game, FSX does not install and you receive a “1722” error message, which represents that a system level failure has occurred.  In most cases, you will receive another error message that is followed by a “1605” installer error message.

To solve the problem, one needs to obtain the Software Licensing System Reset Tool (MSKB928080.exe) and extract the files to C:\MicrosoftKB928080.  If an Open File – Security Warning dialog box appears, click Run.  Now run the Software Licensing System Reset Tool as below:

1. Click Start
2. Click All Programs
3. Click Accessories
4. Click Command Prompt
5. At the command prompt, type the following command in the Open box: C:\MicrosoftKB928080\resetsldl –All
6. Click OK

If you receive a file name error message, a location error message, or a syntax error message, follow these steps:

1. At the command prompt, type “cd c:\” (without quotes) to change the location to drive C
2. Type cd MicrosoftKB928080
3. Type dir for the directory listing.
4. Type resetsldl -All, and then press ENTER.

You are prompted for the license reset and are now good to reinstall FSX again.