Illegal Operations can be caused by several different factors. The following is a listing of the more commonly known reasons for getting Illegal Operations.
TSR's or Third party programs causing memory problems or other things with the program(s) that you are running
The data can not be read properly from the source. The running a program or game with a dirty CD can cause the CD to be read improperly causing an Illegal Operation. Floppy disk which contain errors could cause an illegal operation.
Installing a program or game on a hard disk drive that has errors or is highly fragmented.
Corrupt files.
Memory managers.
Bad, incorrect or not the latest video drivers.
Computer Virus.
Added hardware
Error in program coding
Corruption or problem within Windows.
Bad Memory, invalid bits or physically bad memory.
The Fix:
Third party programs running in the background are one of the more commonly found reasons for Illegal Operations. If you are getting an Illegal Operation when trying to run a game or program it is advised that you temporarily remove or disable the Third Party Programs running in the background to ensuring that these programs are not causing the problem
Additional Information on how to remove TRS can be found on document CHTSR.
If after removing these programs, you run the program(s) or game and no longer see the Illegal Operation pop up, It is advised that you reboot the computer and disable or End Task of each program or TSR one at a time. To attempt to find out which program is causing the Illegal Operation.
Notice from microscopic^earthling:
Wrong forum. Moved to OS.
.
But it works fine on Win XP....strange for a game meant for 95(?). 
just an idea for those who can't fix these problems...
