Creloaded Shopping Cart Bugfix - Customer Details Not Saved

We are a UK seller of laptop and laptop parts and need our current CRELOADED (OSCommerce) website to be developed. Our site has been running for 5 years now but has not been managed / maintained so needs some development. Software version: OSCommerce is CreLoaded v6.2b2b This is a standard configuration but has had some small mods added relating to multiple products management and feeds so that we can import a csv file of products. 1 - Sometimes (about 1 in 10 orders) a customer will place an order on our website and go through checkout e.g. Paypal and make payment. Somehow no customer details are saved during the process, so all we knows is the customer email address! All other orders are fine with customer details being saved. We need this bug fixed. 2 - Some customers are experiencing problems making payment by Paypal (web page errors) and so cannot complete checkout. This seems to happen with about 20% of orders and we don't know why. We would like this identified and fixed. Hopefully these are quite easy for someone to identify and fix who has CreLoaded/OSCommerce experience with knowledge of PHP. Essential: OSCommerce/Creloaded Familiarity Intermediate in MS Excel Good communication skills - English, Give daily updates/work reports, Use Skype or MSN Messenger when online. Must be online for at least 1 hour between GMT 10:00-17:00