How do I ensure other computers have access to files on an external (removable) hard drive?

Question

I have a Seagate GoFlex 3 TB hard drive with tons of random videos on it and a bunch of files for my website, etc (lots of random stuff, ok?). Today I tried to take it to my friend's house thinking I could just plug it into his computer and be able to access all the files just like I always have been able to do with other computers using my mini 3 GB flash drive. However, his computer only allowed him to access a few folders on the drive. The rest of the folders kept telling him he did not have permission. When attempting to change the owner (take ownership) of folders and/or files, the system told us that he was now the owner and would let him open folders, but would still not let him open the files (it would only show a file list for the folder). When I reconnected the drive to my computer at home, I still had access to all files like none of the folders or files had their ownership changed. What do I need to do to make all the files and folders on the drive accessible no matter what computer we plug it into, or at least on both of our computers?

Honestly I don't remember ever setting any security settings for anything on the drive. I assumed it would act just like a flash drive would concerning file permissions. Is it possible that a program such as Windows Media Player automatically changed the file permissions without my knowledge?

I am running Windows 7 Pro and he is running Windows 7 Ultimate. His computer obviously had access to the setup files because it installed the device drivers and everything just fine.

Answer 1

See Evan Anderson's answer to a similar question

Setting ownership and permissions to/for 'Administrators' or 'Users' (as built-in security identifiers) should provide an acceptable result.

As to where your existing ownership/permissions came from... Hard to tell.

Answer 2

If you really want to make it accessible on any computer and don't care about security you can modify the file permissions on the entire drive and add "Everyone" as an authorized user and set the permissions to Full Control. See Picture: Security Properties for the entire drive. To do this: Right click on the drive > Select Properties > Click Edit > Click Add > Click Advanced > Click Find Now. Under Search Results look for Everyone. Double-click Everyone > Click Okay. Under Group or user names: click on Everyone > Now, below the edit button, you'll see Permissions for Everyone. Under Allow check the box for Full Control > Click apply and wait. You'll likely receive an error at some point when the security tab tries to set the permissions for System Volume Information and the Recycle Bin.

You can simply click Continue or Okay and ignore these errors. Now near the bottom you'll see Advanced click on that. Click Everyone > Click Edit. Near the top right you should see Show advanced permissions, click it. Now uncheck Change Permissions and Take Ownership > Click Okay. Under the Add, Remove, Edit buttons check the box that says, "Replace all child object permission entries with inheritable permission entries from this object" and click Apply.

That should take care of it.