After blackout Mac-formatted ext. hard dri...

Here is my best guess and strong suggestion. First do nothing else until you have your work off loaded to some other drive or media....and I mean do nothing....don't even turn it off until this is completed. Once that is done verify your work is there. Then learn to smoke or drink and sing hallelujah.

My best guess is you lost the FAT (file allocation table)...meaning it got (literally) zapped by the power failure (spike) which makes sense since it's continually being accessed. Lacie should have a disk diagnostics program on their website....that loaded onto a diskette or cd would be my first step. It will tell you if the drive is good or not. If good and after you have off loaded your files to a safe media then the fastest solution is probably to reformat and reload your applications then reload your files. I say fastest as (in my twilight years) I have almost (it's a pride thing) given up solving hard problems the hard way...particularly when they can be both hardware and software interrelated.

A couple of other points....uploading to the net your files (even if it costs) or using a bit torrent to transfer to a friends machine (pay for the other drive) or using raid (which I am not a big fan of) or copying them to a one touch....(possibly the least expensive solution (just start it at night...it's not fast the first time and do it daily). You have too much invested to get had by Mother Nature.

Why would I tell you this....well, there was the time I worked all night to finish some code and just as I finished (without saving once) and feeling satisfied I stretched back, extended legs and knocked the plug out of the socket. I also had a computer shop
wipe my disconnected spare duplicate drive at the same time they wiped my master. Today, and I have multiple large projects I work on (mine...not others), and despite more backups in more ways than you can imagine I am still subject to bouts of paranoia.

Lastly....Am not up to date with Mac but at some of the freeware sites I have run across utilities that might be of help. Trying to restore the fat (Windows keeps two copies) might be a possibility and I assume Mac has something similar. But I would only attempt this based on what the drive diagnostics results are....i.e. if you have more than 4 bad clusters it's probably not worth taking the chance of another major disruption. Hope this helps or at least points you in the right direction. Tango