Did you ever resolve this issue with 2005? I've got the same thing going on.
If I drop and recreated the subscription it seems to work for a while but the error messages
always seem to come back. I found a few articles on this about older version of SQL Server.
I'm thinking it's probably the same issue. One of them says to drop and recreated the publisher table which is not a viable option on a 24 hour production system and a 50 million row table. I did notice different version of sp2 on my publisher and subscribers.