If you are trying to upgrade the Oracle Client and an error message is displayed telling you that msvcr71.dll is in use, try the following:
1) Verify that all Oracle services are stopped.
2) Stop the Distributed Transaction Coordinator – In most cases this will solve the issue.
3) Run Process Explorer
a) In the Find menu, click on “Find Handle or DLL” (CTRL F)
b) Type msvcr71.dll and click on Search
c) Go through the list and close the listed applications