FSX won't load up after defragmentation

I bought the boxed FSX Deluxe Edition and when I start the program right
after I install it everything runs fine until startup of a flight. I
set the settings to max after I ran a system test on my comp saying I
could with the 8G of ram, Intel Quad Core and the Nvidia GT220, but it
skipped so I figured it was because of FSX being 15Gb and alot of
fragmented files. So I ran the defrag and restarted my comp and came
back to fly FSX and it wouldn't even start up. I have no idea why it
won't, I've tried doing it from startup, going into the disk itself and
running auto run and still nothing.
Iv'e tried this three times and same results each time.
Thanks in advance
specs:
Asus CG5270
Intel Core2 Quad CPU Q8300 @ 2.50 Ghz
RAM: Four 2048MB RAM each at 800 MHz


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Blue4