Thanks for your help aslain, i tried the run as administrator and it had no effect, i tried disabling my firewall and antivirus and still couldnt get it to run. As i said above it was downloading very slow so I checked my internet speed and it was 8Mb/s DL where usually its around 30MB/s. I couldnt work out what it was so i just did a clean install of windows and now my internet speed is back to normal and I was able to install aslains modpack. So for anyone else it turns out it was probably something to do with my internet settings, antivirus, firewall settings or other windows setting.
Thanks again for your time aslain, it helped alot.