Both 2005 SP3 CU2 and 2005 SP2 CU12 contain fixes for two bugs that cause corruption in LOB data.

The first bug may happen when a column type is converted to varbinary(max), change the large-value-types-out-of-row option to true, insert a row, and then try to update it – described in KB 961648. The second bug may happen when you update an out-of-row LOB value in a database with snapshot isolation enabled – described in KB 962209. Either of these problems will result in a 7105 error:

Msg 7105, Level 22, State 11, Line 1
The Database ID Database ID, Page (N:N), slot N for LOB data type node does not exist. This is usually caused by transactions that can read uncommitted data on a data page. Run DBCC CHECKTABLE.

You can get the fixes at 2005 SP3 CU2 and 2005 SP2 CU12.