Hi, I have a computer running windows 7 (x64) and I am in the process of installing the 2010 AutoCAD Trial.Installation seems to run smoothly until it is finished with Direct x 9 and moves onto the next stage. I get a error message:".NET 3.5 is not installed. AutoCAD 2010 cannot be installed without this component. See your system administrator for more information."I am trying to install the 64 bit version of cad, so its not a matter of me trying to install the wrong version for my system.I tried installing .net 3.5, but it wasn't doing anything, so I googled around and found that 3.5.1 is actually already installed on my computer, and yes, there is a check beside it in Turn Windows Features On or Off (I also found a link to a hotfix that seemed like it might have helped me, but its a corrupt file so I can't use it!)I am completely stumped. Please help!

[QUOTE=tmc5]Hi, I have a computer running windows 7 (x64) and I am in the process of installing the 2010 AutoCAD Trial.Installation seems to run smoothly until it is finished with Direct x 9 and moves onto the next stage. I get a error message:".NET 3.5 is not installed. AutoCAD 2010 cannot be installed without this component. See your system administrator for more information."I am trying to install the 64 bit version of cad, so its not a matter of me trying to install the wrong version for my system.I tried installing .net 3.5, but it wasn't doing anything, so I googled around and found that 3.5.1 is actually already installed on my computer, and yes, there is a check beside it in Turn Windows Features On or Off (I also found a link to a hotfix that seemed like it might have helped me, but its a corrupt file so I can't use it!) I am completely stumped. Please help!
[/QUOTE]So try to install Micosoft.NET 3.5 download from microsoft or from AutoCAD DVD. 

I've tried installing .net 3.5 from microsoft and the installer will not run...  .net 3.5.1 is already installed on my computer. I also do not have the AutoCAD dvd because I', downloading the trial from the Autodesk website.