booting message

[Regnat Nikolaus]

Since a few days I get the follwoing message during boot time:

There are differences between the bootsector and it's backup.
Differences: (offset:original/backup)
28:3d/3f, 29:65/00, 30:9c/00, 71:44/00, 72:41/4f, 73:54/20, 74:45/4e,
75:4e/41, 76:20/4d, 77:20/45, 78:20/00, 79:20/00, 80:20/00, 81:20/00
Not automatically fixing this.

Booting continues after a few seconds. I tried to reinstall grub, but the 
problem's still there. What do I have to do to get rid of this?


Nik