Why must I stop and start apache?

I have a problem when I upload new pages to my server. I use apache 2 with
php 4 something as localhost on WinXP Home and it use to work just fine but
now suddenly I must stop and start apache to be able to see the new pages.
The pages are made in php and I also use mysql wich so far works just fine.
I tried to empty cache and temporary internetfiles but no positive result.
What I know of I have made no changes to the system since the time it worked
fine.
Anyone have a clue?
Ofcourse!

//Berra