I ran into an interesting bug this past wee when trying to install the beta 2 build of Visual Studio 2010. I tried both the web bootstrap install and the full ISO download. I also tried the Ultimate version as well as Professional. Nothing seemed to be working.
It turns out that my machine configuration was the problem. I am running a MacBook Pro for my personal dev machine, mostly so that I can dabble in multiple languages on multiple platforms. I am using Boot Camp to run Windows 7. My Windows partition is smaller than the Boot Camp partition. In this case the .NET 4 Framework installer fails, and this is because it is trying to unpack to the largest fixed disk drive, and it doesn’t fail gracefully if that isn’t writeable. The Microsoft Connect site has a post on this issue.
The workaround posted is to remove the drive letter from the OS X volume. That works, but I wanted to offer up a different solution which may have longer term benefits for users who dual boot like myself. I discovered MacDrive, and it’s a driver which allows Windows to write to an OS X volume. Small download, and it has a free trial period. Problem solved in about 1 minute. You can uninstall the driver when you are done installing or upgrade.
According to the dev team, this bug has already been fixed, but it isn’t in the beta 2 build.