Hello! While it appears Server 2003 is supported - https://www.ccleaner.com/ccleaner/faq/installing/what-operating-systems-does-ccleaner-support - It does not run. 'Not a valid Win32 application' is displayed with the latest release. I tried the last XP supported release also (which does work fine on XP), message similar to 'not a supported operating system' displays. Just a note to admins to either update support page or perhaps fix last XP release (should technically be supported on Server 2003). Thanks!