have downloaded dozens of great planes from this site. Some however, crash FS98.  They display properly in the select aircraft menu.  However, when I select some, I get an FLTSIM98 - Application Error.  The message reads "The Instruction at "0x77c40ac4" referenced memory at "0x0000000c".  Te memory could not be read." Then I'm given the options to terminate by clicking OK or debug by clicking Cancel.  Both drop FS98.  Is this really an application error or hardware problem?

Thanks for the tip.  I downloaded the mdl repair.  When I  ran it, it cleared all of my mdl files.