I'm no authoriy on Incredimail but from what you wrote it seems that you were able to restore your Incredimail to a working state using XP System Restore. If this is the case then you should be able to do the following.

1. Start incredimail and back up all your data (File/Data and Settings Transfer/Transfer To New Computer) Save the backup file somewhere external and safe!

2. Run Wincleaner and let it delete all those files (even the incredimail files).

3. Reinstall incredimail from the original CD and then restore your mail files from the backup file you made earlier(File/Data and Settings Transfer/Transfer From Old Computer).