Hi RoyX23, Welcome to BC.
MS occasionally updates the junk E-mail Filter in Outlook with a more current definition of which e-mail messages should be considered junk e-mail. It is not uncommon for them to screw up your message filter. In fact, august update (kb956077) did exactly that. There was another release (kb955434) the very next day to fix it. There has not been another junk e-mail filter update since then until Nov. of last year, which "sort" of fits your timeline (kb959140).
Removing a junk e-mail filter update is not a real security risk. If it's causing problems, my first choice would be to remove it to see if that is actually the issue. If it is, simply waiting for the next update isn't going to hurt.
To see the list of junk e-mail filter updates for Outlook 03, go here.
There is also a limit as to how many filter rules can be applied in Outlook 03. If you exceed the limit, no more rules will be added no matter how hard you try. The solution is to remove them all and start from scratch again. If Outlook seems to be ignoring any new filters you add, then that is also a possibility though somewhat unlikely.
I totally gave up on e-mail filters in Outlook and have it disabled because it never ends.
I use a third party tool that monitors my e-mail and allows me to view it right on server before I actually download it.
I can pick and choose what gets to my machine and what gets deleted before it reaches my systems. It's 100% effective.