File not accessible D: help please

[Esty]

Hello, I just wanted to get a game to run and I get the error message: " File not accessible". I have never had this problem before, so I am not sure how to go about fixing it :/. I did notice when I put the mds and mdf file into Alcohol soft 120% it only shows the mds file and not the mdf file. The mdf file is about 4.5 gigs big.. If that helps you at all I am running windows xp 32 bit.

Thanks in advance for the help.

If you have any suggestions or ideas please post below!