FATAL ERROR when trying to access linetype drop down menu

FATAL ERROR: Unhandled Access Violation Reading 0x0020 Exception at 4262c2h

I get this error when I try to use the drop down menu to change a linetype of an object. I have had this problem before when I tried to change the acad.lin file to include other line types that used text. These linetypes referenced the standard style name which was using txt.shx font. When I changed the standard font to arial i would get this error, I am guessing, because AutoCAD 2000 couldnt handle different fonts in a line, only something simple like txt.shx.

Now I have a clients drawing which has all kinds of linetypes. Most are missing the .shx info, but I can still view them. They have all kinds of different fonts and now I cannot change my linetypes in the drop down menu without AutoCAD crashing with this error. I think that my CAD cannot handle these linetypes even being in the linetype manager, but I cannot remove them as they are being used.

I know this wasn't explained that clearly, but hopefully people understand generally what I am referring to. I don't know what to change to avoid getting this error.

Thanks for any help.

Apparently it is a windows file error.

Here is a link to the fix- http://simple-pc-help.com/How-To-Safely-Fix-Error-0x0020/

Appreciate the help, but the site looks a bit suspicious. I think I might avoid downloading off of it.