[horde] Encryption error in Horde

[Seb Belcher]

Hiya,
 
 I installed Horde 2.2 and it ran fine for my first login but at the top of
the page was the error:
 
 Warning: Undefined property: _iv in
/home/sebbelcher/public_html/horde/lib/Cipher.php on line 107
 
then once I had logged out I could no longer access Horde, I simply get a
white screen with the above error on.

Any ideas?
 
Cheers,
Seb