Problem restoring my original disk partition

What exactly did you do? To get back the space from the deleted partition you first remove the partition, then you drag the sizing gadget of the remaining partition down to the bottom of the partition map. Then click on the Apply button. What you described you did would cause DU to try and reparition the drive completely.

That means there is a problem with the drive's partition map. This may be due to corruption or it may be the result of how you created and/or removed that small partition. The only recovery is to completely re-partition the drive. This will destroy all the information on the drive meaning you will need some sort of backup before doing anything to recover the drive.

Did your computer come with Lion pre-installed or did you start with Snow Leopard?

Yeah, I sympathize. So, here's what you need to do:

Step One:Repair the Hard Drive and Permissions

Boot from your Snow Leopard Installer disc. After the installer loads select your language and click on the Continue button. When the menu bar appears select Disk Utility from the Installer menu (Utilities menu for Tiger, Leopard or Snow Leopard.) After DU loads select your hard drive entry (mfgr.'s ID and drive size) from the the left side list. In the DU status area you will see an entry for the S.M.A.R.T. status of the hard drive. If it does not say "Verified" then the hard drive is failing or failed. (SMART status is not reported on external Firewire or USB drives.) If the drive is "Verified" then select your OS X volume from the list on the left (sub-entry below the drive entry,) click on the First Aid tab, then click on the Repair Disk button. If DU reports any errors that have been fixed, then re-run Repair Disk until no errors are reported. If no errors are reported click on the Repair Permissions button.

If DU reports errors it cannot fix, then you will need Disk Warrior and/or Tech Tool Pro to repair the drive. If you don't have either of them or if neither of them can fix the drive, then you will need to reformat the drive and reinstall OS X.

Step Two: External Hard Drive Preparation

1. Select your external hard drive (this is the entry with the

mfgr.'s ID and size) from the left side list. Click on the

Partition tab in the DU main window.

2. Under the Volume Scheme heading set the number of partitions from

the drop down menu to one. Set the format type to Mac OS Extended

(Journaled.) Click on the Options button, set the partition scheme to

GUID then click on the OK button. Click on the Partition button and

wait until the process has completed.

Step Three: Clone the old drive to the new drive

1. Select the destination volume from the left side list.

2. Click on the Restore tab in the DU main window.

3. Check the box labeled Erase destination.

4. Select the destination volume from the left side list and drag it to the

Destination entry field.

5. Select the source volume from the left side list and drag it to the

Source entry field.

6. Double-check you got it right, then click on the Restore button.

Source means the internal drive. Destination means the external drive.

Step Four: Repartition and reformat the internal drive and install Snow Leopard

1. Select your internal hard drive (this is the entry with the

mfgr.'s ID and size) from the left side list. Click on the

Partition tab in the DU main window.

2. Under the Volume Scheme heading set the number of partitions from

the drop down menu to one. Set the format type to Mac OS Extended

(Journaled.) Click on the Options button, set the partition scheme to

GUID then click on the OK button. Click on the Partition button and

wait until the process has completed.

3. When formatting is complete quit DU and return to the installer. Now install

Snow Leopard.