Cannot bind to AD from Snow Leopard

Mac OS X Snow Leopard cannot bind to my Active Directory (Tiger, Lion can with no problem). I go to Accounts > Login Options, click Join and enter the details. Upon entering the correct FQDN (domain.int) I get an Active Directory Settings dropdown, into which I enter the correct admin credentials.

I then get an error dropdown which says:

The plugin encountered an error processing request. (10001)

In the Console I have the error:

System Preferences[55582] -[ODCAddServerSheetController handleOtherActionError: gotError: Error Domain=com.apple.OpenDirectory Code=4200 UserInfo=0x2003db6e0 "Custom call 202 to LDAPv3 failed.", An invalid attribute type was provided.

The output of dig -t _ldap._tcp.dc._msdcs.domain.int is:

; <<>> DiG 9.6-ESV-R4-P3 <<>> -t SRV _ldap._tcp.dc._msdcs.domain.int
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 27437
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; QUESTION SECTION:
;_ldap._tcp.dc._msdcs.domain.int. IN    SRV

;; ANSWER SECTION:
_ldap._tcp.dc._msdcs.domain.int. 600 IN SRV 0 100 389 sv1.domain.int.

;; ADDITIONAL SECTION:
sv1.domain.int. 3600    IN  A   192.168.0.109

;; Query time: 9 msec
;; SERVER: 192.168.0.109#53(192.168.0.109)
;; WHEN: Tue Jan 31 14:18:33 2012
;; MSG SIZE  rcvd: 101

I have tried this on two Snow Leopard machines connected to the same network, I get the exact same results with both of them.