"No CD"???

[RB]

I am new to this so please bear with me. I made a copy of SOF. I compared the original with the copy and both are identical in MBs. Whenever I try to play SOF I get an error message stating to insert the CD. The CD is in the drive and spinning. I checked other forums for "Soldier of Fortune", and someone mentioned to "Crack it". My question is which patch should I use for SOF, I have a good copy of the CD. Also what does the patch "No CD" mean?
Thank You for your help.