missing file

Hi
Was doing some cleaning of hard drive and I think I may have lost a dll file. When I run FS2004 I get all the way to fly now and then the screen goes blank and back to the desk top, no FS to be found. I ran a check with Norton's Utilities and get to messages as follows if it help. 1 Microsoft shared.DLL Error "Software\Microsoft\Windows\Current Version\Shared DLL's," refers to a missing file, "C:\Windows\System32\SNdefs.dat."
2 Invalid uninstall Entry "Software\Microsoft\Windows\Current\Version\uninstall\TCE, refers to "Uninstallstring" that refers to "C:\program files\microsoft games\flight dimulator 9, " a file that does not exist.
I have re-installed FS2004 5 times and works maybe once then the same problem. Sorry about the length here but not sure how else to explain. My system is as follows:

HP Pentium 4 CPU 2.60 GHZ 512 MB Ram 120 GIG hard drive

I appreciate any help as I have looked all over and havent found any real solutions. I am not a real computer wiz so will need some coaching here. Thanks in advance ...Tom

Hi tom

What Windows are you running (xp,me)

Also seeing that your running Norton,have you tried to recover the file using the utillities

You're probably running XP on that machine. If so, try doing a system restore to several days ago before you ran Norton. Be careful with that utility (Clean sweep). That was a shared DLL that was wiped, probably part of Windows.