I too am having this problem, I'm a new user setting up my first store using 1.38
When I process a PayPal Express order, everything is fine through the Paypal process but when the transaction is complete and I return to my site I get the Whoops, session expired (it's not a timing issue) and the shopping cart is gone (as it would be as we have just started a new session).
This is definately a IE8 problem, works fine in Firefox and IE8 compatibility mode ( compatibility mode from clicked icon). Tried the Meta tag to force IE7 compatibility but this didn't fix it.
I have removed and reinstalled the PayPal modules and tried the Classic template. I have set up a Sandbox account and still get the problem. I'm sure it's just a session handler mismatch but I'm stuffed if I know where to look or what I would do if I found it
Any help would be appreciated.
Barry








