This is interesting. I've had the "I/O operation failure error" also while compiling under FoxPro for Windows 2.6.

In the past, I've often gone to another PC and compiled my Fox2X application from there as one solution. I've also tried turning off GENSCRNX and 3DBOX and sometimes reached a solution that way. I've also done a USE myfile.scx and looked for any invalid drive references and "hacked in" a revised drive letter.
Another solution has been to migrate the application to VFP .

I haven't always been able to determine the root of the problem.

In the future, I'll also try deleting FoxUser.Dbf and putting a computer CD in the CD drive. Thanks!