Developers occasionally need to undo changes that have already been checked in. Going back to a specific file revision in TortoiseCVS is easy:
Right-click on the file and select to bring up the History Dialog.
Right-click on the revision you need and choose the "Save this revision as..." option.
When the Save As dialog appears, do not click the "Save" button; instead, double-click on the file's name in the directory listing.
Answer "Yes" when TortoiseCVS prompts you to overwrite the file.