Boot sector partition corrupt

Hi

I've been having trouble booting up and this morning it wouldn't boot at all.

A "notice" came up suggesting a repair on the boot system and the result was "Boot Sector for system disk partition is corrupt 0 x 490"

The Computer is an HP EliteBook 8460w
Windows 7
250 Gb SSD

I have succeeded in booting from the battery. (no power pack)

I tried this as a previous HP also had a boot problem which also booted from the battery. I replaced the power pack on that occasion and had no further problem.

I haven't, as yet, tried to boot from a replacement pack but I have powered it from an after market power pack and kept running.

I have backed up all my data using Synctoy and also a windows backup.

Any advice?

Thanks

Graeme