Windows Vista Update

My dell inspiron 1440 laptop show this message during startup&i cudnot lgin also.dll has not been registered?

by ds
(dfer)

My dell inspiron 1440 laptop show this message during startup&i cudnot lgin also.dll has not been registered?
my dell inspiron 1440 laptop show this message during startup&i cudnot login also."dll has not been registered,the program will not work properly" in the category wireless configuration.u get this message when i start the machine,and after clicking ok for this machine the screen becomes blank,ut if i increase the brightness or decrease it,i cud see the change.after few minutes the screensaver comes,but i cudnot login,pls help- me.