.DLL File not found-URGENT!!!!!

I have been have some major problems with my desktop this week.  It seems to me that because I wanted to network my two computers (they were prior to formatting the desktop and reinstalling WIN 98). This computer worked beautifully for about 2 months, just like out of the box.  Now on startup it says that it can't be completed, because .DLL file, C:\windows\system\crtdll.dll could not be found, so I went to the system file checker to try to reinstall the missing files. Now it says that I am missing MSISYS.VXD, on top of already missing NWREDIR.VXD, NWLINK.VXD, NSCL.NXD.   Also should I change the search criteria and if so, what subfolders should I include.

 

Other than the above, the computer will boot up and start and you can use only the basic programs, word, etc.  but when I go to plug the internet (cable) back in, it will work for a few minutes and freeze.  I am having so many problems with this computer, that I really don't know where to start.  It would be great if dell sent info. on what CD and where these files are (such as setup, modem, etc), because I don't have a clue when it ways browse where to look.

I am thinking about reformatting it again but, that took several days and about four different dell techs, and then I couldn't connect to the internet and had the cable company come and set it back up again the guy from the cable company told me that I shouldn't have had to re-format.  ANY HELP OUT THERE.  AGAIN URGENT!!!