Break pedal very hard just after start
 

When I start my S40 2004 the break pedal becomes very hard.
I press hard on it but the car doesn't want to stop.
After 1 minute everything is back to normal.

Any hint what would be the cause?
Is it safe to drive?

The valve that controls the brake vacuum pump might be bad. It is on the front of the booster.

There was a recall for this very thing on the 2000's.

Absolutely it is NOT safe to drive.

Thanks for your kind reply.

Now I know what to do....