Incredimail and cteng files

I’m using Incredimail Build 5683265 under xp-sp2. I noticed recently that this software generates a pile of cteng DAT files in my TEMP folder which cannot be destroyed, even when Incredimail is inactive. You either have to “kill” the files or delete them in safe mode. Anyway they come back whenever you re-use the software.

There's a great deal of bad feedback about Incredimail over the Web. Are they using our pc’s as zombies? Are we better off dropping the software?