hiyohiyo Please enable auto detection feature from "menu > Function > Advanced Feature > Auto Detection".
what would this do? rescan every xxx seconds ? won't this slowdown HDD performance ?
when i restarted CDI, long file copy, that was in progress, was aborted with error like "cannot access file". It seemed like HDD filesystem was detached for a glimpse and all file handles were invalidated. I'm afraid of similar effects on enforced regular rescan.
hiyohiyo 
CrystalDiskInfo
I use case atches, making easy swappign of HDDs, like in inks below.
I wound CDI (on Vista x86) reporting my HDD fault. It was CDI 3.6.4 maybe latest 3.9.3. fixed that, dunno. I looked at it and was shocked to see "Remapped sectors as 100/100/140/0" val/worst/threshold/raw
Then i looked the drive was G: Western 1Tb drive. But i alread replaced it! I made Rescan (F6) and CDI dispayed me correct P: Samsung 1.5 TB disk with Remapped Sectors as "100/100/10"
So i think, that CDI did not saw HDD change, re-queried val/worst, but did not re-queried the threshhold and HDD passport.
What i think would be nice to implement:
1) CDI does monitor hardware attachments/detachments messagies and in time acknowedge drivwe letters and disks changes. 2) CDI as a 2nd line defense, looks whether SMART had suddenly changed in large difference from last reports and if such - rescans drive's passport, threshholds/raws and drive letter.
PS: hardware used o swap drives: dealextreme.com SKU 15208 and 33559 and 19704