This sort of weird thing can also happen if you mix the use of HDToolBox with HDPrep or SCSIConfig.
They all write their own type of RDB to the drive and things can overlap with unpredictable consequences. If something turns on the following day differently though it's worth checking if the drive has bad sectors, if you switched off during a write or if (like me) you get trouble with your interface - particularly SCSI issues.
DiskSalv is a lifesaver but it's always important to either back up your RDB or write down the block limits etc. of each partition so things can be recovered should the RDB be corrupted.
I remember overwriting the RDB but for some reason I had written down the size of each of my partitions and by sheer luck managed to retrieve lost files by re-partitioning the drive, quick-formatting and then using DiskSalv to 'Salvage' the data that always remains on a drive (until it is given a FULL Format).
Keep magnets, amplifiers and unshielded speakers away from your Amiga too!
:-)
