Browsers won't cache a CGI script, but they may cache its output. You can control this somewhat with headers like Cache-control and Expires, but not after the fact.

If it is in fact a problem with a cached page generated by a CGI script, the user should be able to fix the problem by clearing their cache, quitting their browser, then re-visiting the page; or by force-reloading the page in their browser (Shift-Reload in Mozilla/Firefox/Netscape, either Ctrl- or Shift-F5 in IE).