Hi, I'm back,
I did several tests with different versions of sogo, with and without VBoxAdditions, with 2 different versions of VirtualBox in 2 different hosts, and always got the same result.
Seems to me that the problem is related to LDAP authentication, so I went looking for something in /var/log/ldap/current.log
Before the reboot when I login in sogo, the log file shows
@40000000543967711bb3aacc conn=1036 fd=13 ACCEPT from IP=127.0.0.1:38704 (IP=0.0.0.0:389)
@40000000543967711bb7d534 conn=1036 op=0 BIND dn="uid=test2,ou=users,dc=server1,dc=pt" method=128
@40000000543967711bcaad6c conn=1036 op=0 BIND dn="uid=test2,ou=Users,dc=server1,dc=pt" mech=SIMPLE ssf=0
@40000000543967711bcc7e44 conn=1036 op=0 RESULT tag=97 err=0 text=
@40000000543967711bd88c34 conn=1036 op=1 UNBIND
@40000000543967711bd8c6cc conn=1036 fd=13 closed
@4000000054396914384f003c conn=1037 fd=13 ACCEPT from IP=127.0.0.1:38719 (IP=0.0.0.0:389)
@4000000054396914385c2b54 conn=1037 op=0 BIND dn="uid=test2,ou=users,dc=server1,dc=pt" method=128
@4000000054396914385c5e1c conn=1037 op=0 BIND dn="uid=test2,ou=Users,dc=server1,dc=pt" mech=SIMPLE ssf=0
@4000000054396914385c8cfc conn=1037 op=0 RESULT tag=97 err=0 text=
@4000000054396914386468b4 conn=1037 op=1 UNBIND
@400000005439691438647084 conn=1037 fd=13 closed
When I reboot
@40000000543969d5223cf9fc slapd shutdown: waiting for 0 operations/tasks to finish
@40000000543969d52b647794 slapd stopped.
When I try to login again in sogo with no success
@4000000054396a5a29a2da04 conn=1001 fd=13 ACCEPT from IP=127.0.0.1:47155 (IP=0.0.0.0:389)
@4000000054396a5a29a65c74 conn=1001 op=0 BIND dn="cn=test2,ou=groups,dc=server1,dc=pt" method=128
@4000000054396a5a29aca9bc conn=1001 op=0 RESULT tag=97 err=49 text=
@4000000054396a5a2abd23a4 conn=1001 op=1 UNBIND
@4000000054396a5a2abd3b14 conn=1001 fd=13 closed
@4000000054396a5a2ad5dbc4 conn=1002 fd=13 ACCEPT from IP=127.0.0.1:47156 (IP=0.0.0.0:389)
@4000000054396a5a2ad850ac conn=1002 op=0 BIND dn="uid=test2,ou=users,dc=server1,dc=pt" method=128
@4000000054396a5a2ade4bec conn=1002 op=0 RESULT tag=97 err=49 text=
@4000000054396a5a2aea1f44 conn=1002 op=1 UNBIND
@4000000054396a5a2aeca7b4 conn=1002 fd=13 closed
I do not know if it's important, as I have no knowledge of LDAP.
Some LDAP guru could check this ?