For several minutes I could not get IS turned on.
It was turned 'on' but was showing a big red X for off.
Even after rebooting it was off. Then, it turned back on again.
Win XP sp3 H.E.
how long was the machine off since your last shutdown (it takes some time to DL and install the updates)?
Does the problem reoccur?
Matthias has a good point it would be good to know how long the IS didn't receive updates.
It could be the case your computer was turned off for a long time and F-Secure released a Hotfix to the channel. Depending on what part of the product will be hotfixed the F-Secure services will be restarted during hotfix installation process.
Restarting the F-Secure services will then trigger the red cross and notify that AV is off.
Red cross should only be visible for a short time.