I could almost manage this in French, but I won't embarass myself:
Try this:
start, control panel, add or remove programs, Microsoft Antispyware, change,
update.
This has fixed a similar issue for me.
If you are not on build .509 (see help, about) (usually this means you
downloaded before February 16th or so)--you might wish to download the new
build and install that. It will upgrade the version you now have. I'm
uncertain whether you would still need to run the update install--perhaps!
