Can't run Maxima

Hi all,

I have a computer that runs under Windows 8 and I tried to install 
Maxima (version 5.28) in it. When I try to run Maxima, I get this 
looooooong error message:

------------------------------------------------------------
not supported dirname
   while executing
"error [concat [mc "not supported"] "[lindex $res 0]"]"
   (procedure "getURL" line 86)
   invoked from within
"getURL $new contentType mimeheader $post"
   (procedure "OpenMathOpenUrl" line 67)
   invoked from within
"OpenMathOpenUrl $maxima_priv(firstUrl) -toplevel .browser"
------------------------------------------------------------

and so on, and so on.

Any idea?
-- 
Jose Carlos Santos