problem with a full hard drive

I have a Pentium 3, 550 MHz, 40gig hard drive computer with Window XP SP1 OS.

My computer registers that the hard drive is full (less that 1% free space). The mystery is that I have only a few game programs, some music files and digital pic files. Conceivably, the hard drive usage should be closer to 15 or 20 gigs. My problem seems to have began after I attempted to use the Windows Backup program. I am not familiar with the Backup program, so I am not sure I set it up correctly. I set the program to backup every Monday with the backup being saved to another computer's spare hard drive (via network). I noticed a prompt (pop-up Windows generated box) that said the hard drive was getting full after the first time backup was performed. I attempted to backup manually before the scheduled Monday run.

I have since deleted the scheduled backup going through Scheduled Tasks.

I attempted to run defrag, but received a prompt that there was not enough free space (recommended 15%). I proceeded to delete approximately 4 gigs of data (music and pic files). A Windows prompted notice indicated that the block of data was too large to go to the recycle bin (therefore nothing of significant size went to the recycle bin). I deleted the data anyway. However, the analysis function (analyzing size and free space on the drive) in the defrag program did not recognize that any of the data had been deleted. The "My Computer" window also reflects the same hard drive information that the defrag program noted (amount of free space). I ran defrag anyway, which took less than 5 minutes with final results indicating there remained a lot of fragmented files.

First, what is going on with the hard drive?

Subsequent questions:

How can I tell if there is a large file, such as a backup file, that takes an enormous amount of space on my hard drive?

How can I recapture the "dead" free space, if there is any?

What can I do to correct the problem without having to reformat the drive?

I appreciate any help you can offer.

Thanks

 

Sounds like the backup has actually stored itself on the HDD.

To find out whats going on, just use Windows Explorer and look at the files and folders. Its not difficult to look for large files or folders.

Look at the drive space used and free by right clicking it when it shows up under My Computer, select Properties

 

Search for the backup files. They have the extension .bkf
Start / Search then in the "all or part of the file name" box type .bkf
the files will be listed as they are found.
Right click on the file(s) and delete.