>current=select()

The following 2 lines are useless:

>select 0
>free=select()
>
>select 0
>use info && It hangs
>here the second pass through

Yes, because the second time the Info table is already open in other area.
Replace the previous 2 lines with (similar to what you do for student.dbf):

if not used("info")
use info
else
select info
endif

>locate for rtrim(field)="enrollment"
>m.enroll_def=value
>
>if .not. used("student")
> select (free)

Replace the previous line with :
select 0

> use student
> s_open=.f.
>else
> select student
> s_open=.t.
>endif

HTH,
Vlad