I also have this error on clean Windows XP SP3 PRO without updates.
Not every sysadmin installing all updates for various reasons, so you have to check this issue.
P.S. After installing updates getting the same error... Very strange.
That very strange... bsolutely unable to install on Windows XP SP3. This screen appears at very end of installation.
Product: 3CX PhoneSystem -- Error 1720. There is a problem with this Windows Installer package. A script required for this install to complete could not be run. Contact your support personnel or package vendor. Custom action InstallPostgresService script error -2147010895, : Line 15, Column 5,