Problem with disk space after uninstalling BootCamp

I have a Macbook Pro with a 160 GB hard drive (disk utility reads 148.7 GB). Using bootcamp I installed XP on a 32 GB partition. After several problems with trying to get XP to run properly (driver issues) I finally gave up and deleted the partition, again using bootcamp. The problem is that the 32 GB partition seems to have either disappeared or become inaccessible.

Here is what Disk Utility tells me:

Capacity : 148.7 GB (159,697,911,808 Bytes)
Available : 46.1 GB (49,514,029,056 Bytes)
Used : 70.9 GB (76,113,764,352 Bytes)

So, Available space + Used space = 117 GB, which is roughly 32 GB shy of the Capacity. Where did this space go?

The first thing that I tried was the "verify disk" option in Disk Utility. Here's the report on that:

Verifying volume “Macintosh HD”
Checking HFS Plus volume.
Checking Extents Overflow file.
Checking Catalog file.
Checking multi-linked files.
Checking Catalog hierarchy.
Checking Extended Attributes file.
Checking volume bitmap.
Checking volume information.
Volume Header needs minor repair
The volume Macintosh HD needs to be repaired.

Error: The underlying task reported failure on exit

1 HFS volume checked
Volume needs repair

Ok, no big deal, right?......except for the fact that the "repair disk" option is grayed out!

Next, I started looking around the forums here and found that people have had success using Drive Genius to repair their hard disks. I downloaded Drive Genius and here's what it is reporting:

Display Name: Macintosh HD
BSD Name: disk0s2
Drive Title: ST9160821AS Media
Whole: No
Leaf: Yes
Writable: Yes
Mounted: Yes
BSD Major: 14
BSD Minor: 2
Preferred Block Size: 4,096 bytes
Size: 148.73 GB (159,697,911,808 bytes)
Used: 102.62 GB (110,183,989,248 bytes), 69.00%
Available: 46.11 GB (49,513,922,560 bytes), 31.00%
Removable: No
Ejectable: No
Content Hint: Apple_HFS
Content: Apple_HFS
S.M.A.R.T. Status: Verified

So here, the 32 GB partition that I deleted is showing up as "used" space. My next problem is that Drive Genius will not let me perform any tasks on my hard drive other that to "repair permissions." All other utilities in Drive Genius, when I attempt to use them, give me the same error message:

Device Error

Unmount failed for device 'disk0s2' with 'Device is busy (The disk may be in use by an application.)' (0xF8DA0002).

Even after restarting and making sure no apps are running I still get the same error messages. Can anyone help me fix this and reclaim my 32 GB?? Thanks in advance for the help.