I got this using firefox:
ERROR
The requested URL could not be retrieved
While trying to process the request:
POST /rcInstall/steps.php?step=0 HTTP/1.0
Host: www.roundcubeforum.net
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.0.3) Gecko/20060426 Firefox/1.5.0.3
Accept: text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,/;q=0.5
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip,deflate
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7
Keep-Alive: 300
Proxy-Connection: keep-alive
Content-Type: application/x-www-form-urlencoded
Cookie: PHPSESSID=30c54ca5c1c34823d5fe825c6b5ec71a
Pragma: no-cache
The following error was encountered:
* Invalid Request
Some aspect of the HTTP Request is invalid. Possible problems:
* Missing or unknown request method
* Missing URL
* Missing HTTP Identifier (HTTP/1.0)
* Request is too large
* Content-Length missing for POST or PUT requests
* Illegal character in hostname; underscores are not allowed
Generated Fri, 12 May 2006 18:38:28 GMT by lacacheraq1 (Squid/2.1.PATCH2)