commit problems

We have had a problem with postgresql 8.3 on a Windows server 2008. I 
wonder whether there has been any other experiences like this. We have 
connected to Potsgres from Zope via a Psycopg adapter and noticed that 
sometimes when data is inserted via a form in Zope, the data is 
available in Zope but doesn't get committed to the database. This has 
come to a head over the weekend where at least one month's worth of data 
has disappeared and this includes changes to the actual database 
structure - luckily only on a testing machine, but concerning nevertheless.
The data seemed to disappear after we upgraded to the most recent 
version of Zpsycopg2 database adapter, previously we were using version 
1 (I know it's old, we are only testing after all) and have never had 
these sorts of problem before. It's almost as if all the data and 
changes to the db were held in memory, and Postgres continued to work 
fine from there, but when the db adapter was changed and Zope restarted 
everything was cleared from memory.
Has anyone had similar experinces or can anyone cast any light on where 
the problem may lie. To us it seems the db adapter is the most likely 
candidate but we can't understand how this could happen, explanations 
also welcome.
Regards
Garry