java installation problem

I wanted to freshly install jre1.6.0_20. which was giving me some trouble. When ZI try to unistall it it goes to uninstallaion window and at the end says Error 1316.A network error occurred while attempting to read from the file C:Wnidows\installer\jre1.6.0_20-c.msi. I have checked this folder and there is no such file there. I have tried reinstallation by downloading java. Then it says that java already is installed and I am asked to uninstall it. I am unable to manually install java too. What is to be done???