I guess it already was such an issiue when I was still using universal's who.php file!
Since my method is more reliable to 4images's modules, I would deeply recommend to maintain my version of this MOD (especially for security & sessions issues).
Mhm now.. any idea what could be the problem?
Well, I believe, this part, you already know - it's an .htaccess redirection problem.
Would you mind showing your .htaccess readings regarding this action ?