LaCie 1TB external hard disk behaving strangely

[Technopath]

About 3 months ago I bought a LaCie 1TB External Hard Disk, it worked fine although a bit slow when I was using Windows XP SP3 x86, I didn't mind it being slow since I used it mainly for backups, now I installed Windows 7 x64 about a week ago and it worked fine too, but then the problems came:

Windows will hang/freeze and all my USB ports will stop responding when:
- I cut/copy and paste anything from my other disks to the LaCie disk.
- I cut/copy anything from one folder on the LaCie disk to another folder in the same disk.

Copying from the LaCie disk to another disk and deleting stuff works fine though, which is strange.

I checked the permissions and everything was fine, and the fact it hangs and all USB ports stop working indicated that probably wasn't the problem.

I scanned the drive for problems, including bad sectors and none were found.

Then I remembered I installed PowerISO just before the problems started appearing, I uninstalled it and cleaned the registry, restarted and it seemed to work fine again, but sometimes I need to use PowerISO again so I figured I'd just install it when I needed to use it and then uninstall it again, so I installed it again and go figure, the drive wouldn't work. Then I uninstalled and it still wouldn't work. This is pissing me off, any ideas?

Thanks in advance.

By the way, formatting isn't really an option since I have important stuff in there that is just too big to copy over to my other disks.

[GiGaBiTe]

Try CDBurnerXP.

[url]http://cdburnerxp.se/[/url]

[Technopath]

I'll try that instead of PowerISO.

As for my problem, I checked the permissions for accessing the drive and my windows account wasn't there, I suspect it got deleted for some strange reason, I added myself to the permissions and the Full Control and Write permissions were unchecked, that might be what was causing the problem, I activated them and clicked Apply and it tried to write a file to the disk but said I didn't have permission then it started modifying the permissions on the files already on the drive. I'm gonna check if it works now, if it doesn't I'll log in as Administrator and change it to see if that fixes it.