Thanks for the quick reply.
I do not have eStore_post_payment_debug.log. Instead I have eStore_payment_debug.log, and it is empty after running a transaction in debug mode (it is write-enabled).
ipn_handle_debug.log is:
[09/06/2011 9:13 AM] - SUCCESS :Paypal Class Initiated by 80.40.220.33
[09/06/2011 9:13 AM] - SUCCESS :Post string :
[09/06/2011 9:13 AM] - SUCCESS :Connection to http://www.paypal.com successfuly completed.
[09/06/2011 9:13 AM] - FAILURE :IPN validation failed.
[09/06/2011 9:13 AM] - SUCCESS :Paypal class finished.
------------------------------------------------------------------
[09/06/2011 9:13 AM] - SUCCESS :Paypal Class Initiated by 80.40.220.33
[09/06/2011 9:13 AM] - SUCCESS :Post string :
[09/06/2011 9:13 AM] - SUCCESS :Connection to http://www.paypal.com successfuly completed.
[09/06/2011 9:13 AM] - FAILURE :IPN validation failed.
[09/06/2011 9:13 AM] - SUCCESS :Paypal class finished.
------------------------------------------------------------------
[09/06/2011 9:15 AM] - SUCCESS :Paypal Class Initiated by 66.211.170.66
[09/06/2011 9:15 AM] - SUCCESS :Post string :[admin deleted post data]
[09/06/2011 9:15 AM] - SUCCESS :Connection to http://www.paypal.com successfuly completed.
[09/06/2011 9:15 AM] - SUCCESS :IPN successfully verified.
[09/06/2011 9:15 AM] - SUCCESS :Creating product Information to send.
[09/06/2011 9:15 AM] - SUCCESS :Transaction Type: Shopping Cart
[09/06/2011 9:15 AM] - SUCCESS :Number of Cart Items: 1
[09/06/2011 9:15 AM] - SUCCESS :Item Number: 37
[09/06/2011 9:15 AM] - SUCCESS :Item Name: xxxxxxxxxxxxxx
[09/06/2011 9:15 AM] - SUCCESS :Item Quantity: 1
[09/06/2011 9:15 AM] - SUCCESS :Item Total: 0.01
[09/06/2011 9:15 AM] - SUCCESS :Item Currency: GBP
[09/06/2011 9:15 AM] - FAILURE :Wrong Product Price Detected! Actual Product Price : 125 Amount Paid: 0.01
[09/06/2011 9:15 AM] - FAILURE :IPN product validation failed.
[09/06/2011 9:15 AM] - SUCCESS :Paypal class finished.
------------------------------------------------------------------