>>881
This is an interesting error–are you seeing any thumbnails at all, or are only a few broken? Are only thumbnails for new files broken? Did the thumbnails work on your previous HDD?
Hydrus doesn't care what type of drive is running on. If you copy the whole db directory to a new location, I cannot think of a reason why thumbnails would not load properly, unless perhaps the client does not have write permission on the thumbnails folder and so cannot generate a resized thumbnail when first requested to.
Did you copy hydrus to 'program files'? That can cause problems, because Windows doesn't like official programs writing to their own directories. If you did, you can get around the problem by either running hydrus as administrator or moving it to a simpler path like C:\hydrus.
If you discover you are somehow missing your thumbnail files, you can go database->maintenance->regenerate all thumbnails, to get the client to go through all your original files and regen them. This will take a long time if you have a lot of files, though.