A serious problem exists with Windows Vista when using F-Secure product, a problem which a lot of users experience. The problem is that when specific versions of F-Secure products are installed Windows enters a continuous boot-loop when installing Windows Update. This issue appears as
Configuring updates stage 3 of 3. 0% complete
after which the computer reboots and reboots and reboots…
The last few weeks I have seen this issue being asked almost every day in the forums over at www.alltomxp.se/forum. Anyway, for the solution have a look at the F-Secure guide or take a look at the MS KB article.