Msvcr71.dll missing causes Oracle connection failure

Today, in order to test Orcas, I installed Oracle instant client on the VM and still cannot connect to Oracle in Visual Studio 2005, which I have done many times in the past, in the past, the problem was nothing more than the tns_admin environment variable and tnsnames. the ora file, Path, and Oracle Instant Client directory permissions are all correct. Therefore, install a PLSQL command and try to connect to the database. The result is as follows:

Plsqldev.exe-unable to locate component
This application has failed to start because msvcr71.dll was not found. Re-installing the application may fix this problem.

So copy one copy from another machine, PLSQL runs normally, and try vs2005 again. But why is msvcr71.dll missing.