Our PSS team just debugged this problem.  When trying to install VS with crystal reports, a custom action tries to execute and fails.

The WriteKeycodeToRegistryAction.6F2B3983_59B8_11D3_B360_00A0C9DA500E Custom action fails because it relies on dbghelp.dll being present in the \windows\system32 directory. 

If you run into this issue, repair your operating system to get dbghelp.dll (or copy it from another machine).