Crazy order problem: customer charged, product not removed/added to invoice

Okay I had a very weird problem today with my store (v 1.3.7). A customer placed an order for two things. She was charged the correct total and paid via Paypal. However, the following glitches happened:

1. the second product wasn't removed from the store (it remained quantity: 1)

2. the second product doesn't appear on the invoice (BUT the total on the invoice is correct - you just can't tell where the other $20 is coming from)

3. the comments she added to the order don't appear on the invoice

Help?

So does the order show up on your admin CP?

Yes, but it looks like this:

1 x [product name] $20.00

                                        Sub-Total: $40.00 

United States Postal Service (First-Class Mail (2 - 5 days)): $1.45
Gift Wrap: $0.00
Total: $41.45

So this happens to this particular product only. Has it ever been purchased before? Is there anything particular about this product? (Or you don't even know what it is?)
Sometimes I have Paypal not reported the whole order back to the store, but this is rare.

All of my products are one-of-a-kind so I only sell each one once. I know what it is because the customer emailed me to ask me why it wasn't showing up when she logged in to look at her order, but there isn't anything different about it vs. other products.

CRAP it happened AGAIN! More info:

This is only happening with Paypal orders. I have processed three credit card orders without a problem since the screwed up paypal order I posted about above. Just got another Paypal order and it's also messed up. It looks like this:

1 x [product] $12.00
Sub-Total: $42.00
United States Postal Service (First-Class Mail (2 - 5 days)): $1.45
Gift Wrap: $0.00
Total: $43.45

I'm just going to disable Paypal until I figure out what's going on. Heeeelp!

You said you're using v1.3.7.
Have you installed the June 17 PayPal patch?
http://www.zen-cart.com/forum/showthread.php?t=56216

What other addons/contributions are installed?

Have you enabled PayPal debug logging? Please post a link to a zipped copy of logs related to the transactions in question.
http://www.zen-cart.com/forum/showthread.php?t=61199

Can you replicate the problem on-demand?

What's unique to these orders? Are they all using gift certificates in some way?

I think I've narrowed this problem down to the gift wrap add-on. I ran a series of test transactions and when I add gift wrap to my order it drops the products (and the gift wrap) out of the cart either on the way to or back from Paypal.

I disabled that add-on through the admin center and processed an order without a problem. Here are the logs: https://dichroicjewelry.net/logs/