Hi, are you running in medium trust? I'm seeing a lot of errors that say "this error is expected when running in Medium trust or lower". Later, there is a file permissions error that looks like it's coming from NeatUpload. However, per this page of the documentation, I don't think NeatUpload is supposed to be used when running in medium trust.
So my guess is that if you are in medium trust you need to modify your Web.config as per the above link; or if you are running in full trust you need to fix permissions on your data and/or app_data directories as documented here.
Disclaimer: I'm not an expert on running in medium trust, just trying to help out, for what it's worth. This may give you a place to get started until someone more qualified takes a crack at this.