I have an image upload script i just created byt for some reason i am getting this errorl, please help me:

Warning: move_uploaded_file() [function.move-uploaded-file]: Unable to move 'C:\DOCUME~1\PC\LOCALS~1\Temp\php3DA.tmp' to '' in C:\apachefriends\PHP\myscrpt\upload-image.php on line 211

It worked yesterday but i don't know what i did, and now its giving me error