I really can't imagine what might cause this. Do you have inventory control that might have automatically removed items but then not updated the cart properly? Is this display directly from the cart or from the database? Maybe the insert into the database had issues.
Did you try adding the exact same items to the cart?
In order to solve an issue I always have to be able to reproduce it. Otherwise I wouldn't be able to test if the fix worked and I wouldn't really know what to fix at all if it can't be reproduced. So the first challenge will be to figure out the exact steps to try to reproduce it.
If you send me FTP access then I can take a look a the code to see if I can spot something that would help me reproduce it. Is that screen grab from an email or from a cart display?
