When the LDAP attribute "userParameters" is set in the Primary DC (In my case Windows Server 2008 Small Business Server) than Samba dies when you request Userinformation about the user who has data set in this attribute.
Under SBS the attribute userParameters is set with the following data:
(I think its UTF-8 encoded)
After deleting this Attributedata I can user the user Account without samba crash.
*** Bug 10401 has been marked as a duplicate of this bug. ***
Created attachment 9984 [details]
Patch for ldb_val to lsa_BinaryString conversation
The attached patch should fix this issue.