Restore points are always something with seem to work when they want to. I find when using a restore point from a windows update it always seems to work fine but when you create your own restore point and try and roll back to that it comes up saying restore failed or at least that is what used to happen a lot to me when i used Vista. Now i have a new machine with Windows 7 i have hardly ever had to use a resore point. I find restoring from a system image works much better.