Right click or Control Left click on the drive icon and go to Get Info. There you can unlock it and set the permissions.
I've done that but still cannot unlock the icon. I have opened the small lock from entering my computer password XXXXX I cannot open the lock on the larger icon, itself. the error message says could not be modified. I can't get an further than the sharing permissions. I change them to my name and then I tried changing to "everyone" Still cannot open the lock.
Please go to the Apple logo on the upper left of the screen, go to About This Mac, and tell me the System Version, the Processor and the Memory.Then go to Macintosh HD, then go to Applications folder inside that is another folder called Utilities inside that is an application called Disk Utility. Double click on that and when it opens you will see your hard drive on the left. Highlight your hard drive and click on Verify Disk on the right. If that is OK click on Repair Permissions. If Verify Disk is not OK try to Repair.
Sorry do that for both drives you will only be able to Repair Permissions on the system drive.
I did the repair disc function and still cannot unlock it. Is there a way that I can just reset the permissions from scratch. I don't normally do this stuff so I guess I'm still doing something wrong.
In answer to your question, it is a 1.6 Ghz G5. I have OSX 10.5.8 4 gig ram.