After repeated download attempts using both Firefox and IE, repeated attempts to run zaSuiteSetup_91_603_000_en.exe produce the error message "signature of this installer cannot be validated". Attempts to download and run the current trial version, zaSuiteSetup_91_507_000_en.exe produce the same result but attempts to run a long-ago downloaded version of zaSuiteSetup_91_008_000_en.exe (which I am currently running) work just fine. Any suggestions? WinXP Pro SP3. Thanks.