I understand the problem with the dll v3 but my question is this. According to PayPal this dll will no longer be supported after Sept 1, 2009 where everyone will have to use SDK 4.3 either ASP.Net or the https version. Also in there instructions for 3rd party solutions they list Webassist as being complient with the Payflow Pro updates.
"WebAssist Version 4.5.0 includes the Payflow Pro updates.
If you are a 4.0 cart owner, please go to the WebAssist site for assistance with downloading the latest 4.5.0 version." That is the version that I have installed and apparently it is not updated to the new SDK or it is not working correctly.