I assume you've already installed the newest version of Java using the JRE offline installer (installed before installing LW) and you still have the LW offline installer exe on your computer. Also, you do not have any Anti-Spyware program running that sees LW as a threat and hence prevents it from being installed properly.
Given that I'd reckon first to right click the LW icon on your desktop, go to Properties>Compatibility and change the Compatibility mode to Windows NT or Windowns 2000. Then try to install LW again.
If that doesn't work, restart your computer in save mode and try to install LW when booted in save mode.
If that should fail as well, I'd think it will be time to defragment your HDD.
