Here is a list of issues about comments and how to troubleshooting them for Ultimate DNN Blog Module – SunBlogNuke.

Q: We just found out lots of event log with error information "That assembly does not allow partially trusted callers" if comments feature active. How to fix this issue?
A: That is caused by the assembly 'Recaptcha.dll' for Google reCAPTCHA control. If you are using the older version than v5.3.1, please refer to this post with related workaround - http://www.sunblognuke.com/blog/entryid/479/fixed-recaptcha-issue-with-sunblognuke.aspx; Or simply upgrade SunBlogNuke with the latest package to exclude this bug.

Q: Are anonymous comments supported in SunBlog? And I find those comment settings a bit confusing also.
A: Yes, it supports. Please refer to the post 2 Easy Ways to Customize DNN Blog Module::SunBlogNuke, which clarify matters in detail.

Q: After upgrading to SunBlog 4.0, submitting a comment always produces a popup "could not post your comment" error but actually the comment have been saved into DB. When refreshing the current post, the new comment will be there.

A: Try to fix it as follows:

1) Login with your host account
2) Go to host->sql page
3) Copy the script below into textbox and click 'execute' with checking option [Run as script]:
DELETE FROM {databaseOwner}{objectQualifier}SunBlog_Settings WHERE LOWER([Key]) = 'theme' AND LOWER([Value]) = 'default'
GO
4) Restart app in the Host Settings. That is all.

Q: Can’t post comments and it always popups "Sorry, your comment is not updated successfully. Please contact blog owner."

A: Try to fix it as follows:

1) Open up the web.config of your website

2) Find those elements below and check out whether there exists the child element as follows. If not please append them.

in the httpHandlers element:

<remove verb="*" path="*.asmx" />
<add verb="*" path="*.asmx" validate="false" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />

in the assemblyBinding element:

<dependentAssembly xmlns="urn:schemas-microsoft-com:asm.v1">
  <assemblyIdentity name="System.Web.Extensions" publicKeyToken="31bf3856ad364e35" />
  <bindingRedirect oldVersion="1.0.0.0-1.1.0.0" newVersion="3.5.0.0" />
</dependentAssembly>
<dependentAssembly xmlns="urn:schemas-microsoft-com:asm.v1">
  <assemblyIdentity name="System.Web.Extensions.Design" publicKeyToken="31bf3856ad364e35" />
  <bindingRedirect oldVersion="1.0.0.0-1.1.0.0" newVersion="3.5.0.0" />
</dependentAssembly>