Very Computer

My partition table looks like this:

Disk /dev/hda: 64 heads, 63 sectors, 621 cylinders
Units = cylinders of 4032 * 512 bytes

   Device Boot   Begin    Start      End   Blocks   Id  System
/dev/hda1   *        1        1      331   667264+   6  DOS 16-bit >=32M
/dev/hda2          332      332      340    18144   82  Linux swap
/dev/hda3          341      341      621   566496   83  Linux native
Warning: invalid flag 0000 of partition table 4 will be corrected by w(rite)

Does anyone know what that last warning means, and how i can fix it.

thanks!