There are two primary reasons that I have found for your error message. They both have to do with where the FOXUSER.DBF file is kept.
1. The first possibility occurs when you are in an operating system such as Win 2K or Win XP where each individual workstation user has their own set of file access privilages.
If the directory where the FOXUSER.DBF table is kept does not allow Full Access rights to Everyone, then some users will get this error while others may not.
You say that "There is a foxuser.dbf/fpt in the current directory", but does Everyone have READ & WRITE privilages to that directory?
2. The second possibility is that the directory where the FOXUSER.DBF file is kept may not be accessible at all and/or not mapped to the user's workstation.
If you are using a CONFIG.FPW launch file, check it to see if a directory is referenced which is not present and/or not accessible to the user's workstation.
Could it be that the FOXUSER.DBF resides in the "current" directory, but maybe you are using a CONFIG.FPW file which makes VFP want it to be elsewhere?
Good Luck,
JRB-Bldr