SSO with single User not working

Hi,

We have NSM 6.303 in Place with 3 eDirectory Groups and Profile assigned to
it. SSO is activated.
For a absolutly unknown reason, just one User is not able to browse
anything else, that's in the Whitelist. Error on Astaro:
No matching scanner profile found for '@'; 'ip','http-request'
In the Authentication Log:
2006:10:03-10:26:14 (none) aua[20742]: U:10.5.2.100 F:http R:OK C:edir
2006:10:03-10:26:14 (none) aua[20741]: U:10.5.2.100 F:http R:OK C:edir
2006:10:03-10:26:14 (none) aua[20739]: U:10.5.2.100 F:http R:OK C:edir
2006:10:03-10:26:14 (none) aua[20740]: U:10.5.2.100 F:http R:OK C:edir
2006:10:03-10:28:57 (none) aua[3278]: U:10.5.2.100 F:http R:OK [] C:cached
2006:10:03-10:44:24 (none) aua[3278]: Discarded cache.
2006:10:03-10:44:28 (none) aua[27249]: U:10.5.2.100 F:http R:OK C:edir
2006:10:03-11:06:47 (none) aua[3278]: Discarded cache.
2006:10:03-11:06:51 (none) aua[2212]: U:10.5.2.100 F:http R:OK C:edir
2006:10:03-11:15:47 (none) aua[3278]: Discarded cache.
2006:10:03-11:15:51 (none) aua[5236]: U:10.5.2.100 F:http R:OK C:edir

Even with a Profile just for this User, it will not work. Only if I
deactivate the SSO and log in the User manually, it works also for this
User. Every other User in this Group or also in this Context it is working.

The User has a couple workstations, but we also tried with other Users with
multiple workstations - doesn't seem to be a problem for other's.
Does anyone know this problem, or even better a Tip what to do?
Regards,
Tom