My Friend if Modx Works fine in IE, Crome etc... and only have problems in Firefox... that is the problem Firefox!!
so is just configuration.
1. Type “about:config” in the location bar, and press Enter.
2 In the filter box, type “referer” and press Enter. This should leave you with one preference, network.http.sendRefererHeader. This is probably set to 0.
3 Right click on network.http.sendRefererHeader and select “Modify”
- Just change it to 2
and thats all.
Are just some things about security in firefox...
I HOPE THAT WORKS FOR YOU TOO, MORE INFORMATION HERE: