Paypal Standard not working

I can not get Paypal Standard to work on my site. I have never had this issue before with Opencart. I have installed the latest version (3.0.2.0) but I get the error message "Things don't appear to be working at the moment. Please try again later." I also notice that the end of the paypal URL the following ID is displayed BAD_INPUT_ERROR. Any help would be appreciated.

I have the same issue with BluePay.
It seems that the payment modules that comes free with OC don't work too well.

I'm having the same issue. Did you guys every get it to work?