Custom Fields continue to disappear linked to possible IPN error.

[Xtreme4U2NV]

So, no matter what I do, the custom fields I make continue to disappear with every purchase.

I have checked everything, can't seem to find the issue.  Now, whenever someone makes a purchase, for some reason I keep getting the "IPN Amount change detected. The amount sent ()  did not match the amount due" error email.

The thing is, the IPN is the IPN from the paypal, so how do I work this?  Is it possible I have to take in to account paypal's service fees when pricing stuff?

Also, on a side note, when I click on order details, because the custom field option people have previously selected have disappeared.  They have two options, style and colour, both of which aren't there any more.