We need your correct forum url when posting a support question.

Tip:

a:  If you are on smfforfree,    smfforfree2,  smfforfree3,  smfforfree4 use the dropdown box.
     Be sure you have chosen the correct extension in the dropdown box:
     Do not put in your entire url.  Put ONLY the name of your forum.. the part before smfforfree.
b:  If you are on freesmfhosting or mysmf or another service hosted by SMF for FREE
     Do not use the box and dropdown - type your url in the post. 

Check your cookie settings, see how strict you have them set.  Could be an issue with your cookies.
If you are using a redirect service turn cloaking off.