Hi, W3FSY. I'm a long-time Spybot S&D user, currently using version 1.6.2.46 on Windows XP SP3. I think 1.6.2.46 is the latest release version. I do not have any error messages in the Avast Log Viewer or the system Event Viewer.
The part I do not understand is that Spybot S.&D. does not start with Computer "Startup", as far as I know. It is possible that Secure Shredder Aplication does start on bootup.
Spybot is not supposed to start on computer startup, unless you've configured it to do that. The default Advanced setting is System start: No automation. The things that might affect your system when the Spybot program isn't running could be its Tea Timer or SDHelper. They are controlled by the Tools > Resident settings. Tea Timer is automatically started on computer startup and runs continually in the background. It does a bit too much for my taste, so I have that unticked. I do have SDHelper, Spybot's IE bad download blocker checked. It should affect only IE.
Shredder is a separate program, and it doesn't start up with the computer either. It's run only when it's needed, either automatically by Spybot or by the user when manually shredding files.
I went to the Spybot S.&D. forum and did read posts to see if others were having any problems. There were some complaints of errors being recorded, but they were caused by clearing of temp files prior to doing a scan with S S.&D.
I recommend unticking the "Offer to clean the temporary files folder setting". It's not necessary and could easily delete too much, causing problems.
Sorry I can't be more helpful, but I'm glad to hear that, except for the puzzling messages, Avast is still giving you full-time protection.