i cannot DL the new patch =(

when i go to install the new verison of secondlife, as i always do when there is a update, it gets to the screen where i press INSTALL, i press it like always and after a few seconds of it "checking for permisson to instal" i get a pop up that says ::Error opening for writing file:: then it gives me the choice to abort the install retry or ignore, when i press ignore it moves to the next file in the DL and i get the same message

anyideas>?
cause im clueless

pls help
~~Soli