i am trying to upgrade my laptop from vista to 7 and every time i try to do it goes through just fine until it gets to the transferring files stage and then it gets to 49% and then hangs there and doesnt move. after awhile an error message comes up saying "windows cannot copy files required for installation. the files may be corrupt or missing. make sure all files required for installation are available, and restart the installation. error code: 0x80070017" I dont know what to do next. any ideas?