Maybe there's some type of an conflict between S&D resident protection and the new avast! 5.x version--it does have a new AV/AS and Heuristics engines. Know in the past that S&D had issuses with other security software e.g., BitDefender.
As to your "UNSECURED too often" problem, do not have anything help to offer. I'm using custom install of AIS 5 on three Win XP SP3 systems and have not yet encountered what you're experiencing.
As to S&D, was a longtime S&D user until I started using BitDefeder 8 AV and had issues. I dropped S&D and switched to SAS free, and purchase SAS Pro upgrade lifetime license for $19.95.
Reason why I dropped S&D is even back then it was falling behind the other spyware apps as to detection and removal.
Have not seen any recent new tests/reviews of the newer S&D 1.4 and 1.5.x versions that S&D did very well; e.g.:
http://www.pcmag.com/article2/0,2817,2261193,00.aspYou can use SAS free for awhile, and will eventually get an opportunity to purchase a lifetime license for the Pro version for a reduced price. I also have the paid version of Malwarebytes' Anti-Malware. If I'm going to use and rely on any software on a daily basis I'll purchase or provide a donation to support it.
Hence as to your Poll I selected "Combination": SAS Pro on-demand, and Malwarebytes' Anti-Malware with the resident real-time protection.
As to your post "Well, what if the user is not willing to, or not in a position to pay that lifetime license fee, then what would he resort to??"
If not willing then its about time they learned
TANSTAAFL If truly in a position that one cannot afford to pay $20 for lifetime license, guess they would have rely on using one of the free apps available or do without. Though would think that most that have the means (i.e., PC and ISP) to use the internet would being be able to afford $20.