Hello, if you are getting pending orders when using Paypal standard method, you may want to check the underlying reason within Paypal.com.
Please follow these steps:
History -> IPN History
Click on the Message ID link:
Check http response code:
Or other details.
If the code is not 200, then you got a problem. See the list here: http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html
404: Page not found, - maybe a https or subdomain problem
500: Php fatal error usually - check your php error logs
50x: Usually blocked by your internal proxy, maybe http1.0 is not allowed or Paypal's user agent is not accepted by htaccess or web server configuration
3xx: Some redirect -> your SEF or htaccess did a redirect which broke the IPN message
Best regards, Stan