Fusion reads the list of VMs you have.
In that list your Windows dev entry references a full path like /home/vms/under-the-oak-trees/aunt-dorothies-vms/windows dev/windows dev.vmx

All you need to check now is wether a vmx-file with the listed name exists in the specified path.

If the path is invalid == problem solved - fix the path
If the vmx-file is not readable to your account == problem solved - fix permissions
If the vmx-file is invalid -- problem solved - fix the syntax