This is a difficult problem. Because the program you installed before was in the installation format of Windows Installer (MSI for short), although it was uninstalled, the installation file still exists in the system hidden directory of Windows\Installer. The complete solution is to download a windows installation cleanup (Microsoft's own uninstallation software, which can be used to perfectly uninstall a series of software with Windows Installer installation format). After installation, select XXX program, click Delete, and then reinstall. (xyz58 19 idea space-time)
After uninstalling, try to install Adobe Acrobat 9 (application platform: WinXP/Win7) again. Adobe Acrobat 8 (running environment: Win2003, WinXP, Win2000) may not be compatible with Win7.