eqgame.exe - System Error

[Yanomamo]

I tried searching around and i've seen some similar stuff but nothing addressing the exact error I have here

I've been playing perfectly fine every day until last night when i tried to start everquest and got this error:

eqgame.exe - System Error
The program can't start because DSETUP.dll is missing from your computer. Try reinstalling the program to fix this problem.

I mean i could go ahead and reinstall EQ but I'm pretty confused why this even started happening. There was no patch or anything and I haven't changed anything. Anyone have thoughts?