Trying to install the Lightroom 5.3 64-bit update on Windows 7, I get to the page that says "Out of disk space. Disk space required for installation exceeds available disk space". When I click on another drive, I get an error "Error 2803. Dialog View did not find a record for the dialog NoDialog".
If you really only have 911MB left on your C drive, and your C drive is your boot drive, you need to clear more space regardless of what's happening with the installer. Windows won't be able to run properly with so little space. If you clean that up, you should even find your computer runs more smoothly, so it'll be worth the effort.