I'm guessing what you are seeing is corruption of the drive’s FAT. This is sometimes easily solvable by running a drive diagnostic called chkdsk and sometimes not easily solvable.

First things first: make sure you have a backup of everything you care about.

Once that’s done:

Open a command window and run the disk diagnostic called chkdsk as follows:

Type “Chkdsk c: /f /r” ((without the quotation marks)and hit the enter key)

Chkdsk will return the following:

“The type of the file system is NTFS.
Cannot lock current drive.”

“Chkdsk cannot run because the volume is in use by another
process. Would you like to schedule this volume to be
checked the next time the system restarts? (Y/N)”

select y and hit enter again

You’ll need to reboot the computer at some point. The bigger the drive the longer it takes chkdsk to run. It is a good one to let run over night.

After chkdsk completes, see if the application data directory is still not there.

If it is not, it’ll be quicker to start over than to try and troubleshot.

If that solves the problem, except for outlook: the next step is to build a new profile for Outlook. This will separate Outlook from the data set it holds. This will tell you if the problem is Outlook or the data set. But from what you've described , the problem is likely lost parts of the program.

If you need to start over, look for the Dell supplied CD which says it’s for reinstalling the OS. Someone above mentioned one way to get the computer to boot to the CD when it comes up. When you get the install program to load, select the option to reformat the hard drive rather than fix a corrupted install. But you can try and do that if you want first.

The problem you describe is a media related error and not an OS related error so fixing the install won't solve it. It takes about 3-4 hours to do a full build, of which, maybe 30 minutes is hands on the keyboard