problems formatting/deleting files from external hard drive

[nikko]

I have a Maxtor 120 GB external hard drive that I backed up some files on. I want to delete everything that's on there, though, and start my back-up from scratch. There are a few files that it just won't let me delete, for some reason. Everytime I try to delete the folder, it says "such and such file cannot be deleted. Please make sure the path and/or filename is correct". what the hell? i tried to delete each file individually, but no go. Finally, I was prepared to just reformat the drive but when I tried, I got the following message: "Windows cannot format this drive. Quit any disk utilities or other programs that are using this drive and make sure that no window is displaying the contents of the drive. then try formatting again." Any idea what gives? I don't know what program could be using this drive and no other windows were open. I even rebooted several times but to no avail. Any ideas on how to troubleshoot this would be much appreciated. Thanks.