How can I check an archive for CRC errors without actually unzipping it?

This can be done using either Winrar or Winace. The first step is to double-click on the archive you wish to validate to open it. If you are using Winrar, select the 'commands' option from the menu and scroll down the list until you find 'test archived files' and click on this option. Alternatively, if you are using Winace, select 'archive' from the menu bar followed by 'test archive'.

Now get on with doing something useful until the CRC checking process is complete - ah, the joys of multi-tasking. Once finished, look for the words 'no errors found'. If receive this all-clear message you can assume your files are A-OK. If it's bad news you will see the message 'CRC error' adjacent to the file which was currently being processed when the log was created. If this happens, you can either download the archive again and re-check it for errors, or attempt to repair it using Winrar or Winrar (I've covered the procedure in another entry so feel free to use the search engine).