On larger file, yep--I've seen that. Sometimes it's a completely different file. Sometimes it's exactly what you really want.

On the 2nd part I have to question your conclusion. If you have a partial file and a completed file where the partial file represents a portion of the complete file, you should be able to CRC blocks until failue and then pick up with a "resume" function. It wouldn't have to result in corruption.

This would also be extremely handy in cases where you are downloading a partially downloaded file and then find the complete version. The real trick would be modifing the UI so the user can indicate both files should be the same file and then selecting the filename to be used for the save.

ThePowerTool