problem with new hard drive

[Jrusso]

I just purchased a new Seagate ultra ata 120 gb drive which I installed in an external inclosure. The inclosure has both usb & firewie ports, so far I have been using the fire wire, but my problem does not lie in the connection. I formatted the drive with Partition Magic which semmed to work fine, I set up 2 NTFS logical partitians within 1 extended partitian which inturn lies in a primary partitian. This is all done by the software automatically, and I have used it before on my internal hard drive while it had data on it with out a hitch. When I install this ext drive it appears to be fine- I can store data to it, transfer from it ect.... but when I re start my computer and try to access anything on the drive I get an error message saying that the files are corrupted or unreadable.If I look at the drive with Partitian Magic the space comes up unallocated or it shows the partitions but the drive names are all screwed up.(this has happened twice in a row after installing this drive). Do I have really bad luck and get a bad drive out of the box, or is there something I did not do correctly?