Hi Flos888 and welcome.
A Sense Error message means that an attempt to read/write to the hard drive has failed. In most cases this indicates a failed hard drive or damaged wiring to the hard drive.
It is likely that you will need to replace the hard disc and then use the Recovery Discs to reload the original software onto the new drive. This will return the Vaio to its original factory condition and you will need to reinstall rather a lot of updates and a lot of software from the last 10 years.
Before doing this, you can try to repair the system software if this has become corrupt and your drive is OK but to do this, you will need to borrow a Windows XP Pro Installation Disc and boot into the Recovery Console and try to repair the boot sectors and system software. There is a useful guide here: -
http://www.wikihow.com/Fix-Ntoskrnl.exe-Missing-or-Corrupt-Error
However, my guess would be that the hard drive has failed and needs replacement. A 160 GB IDE 3.5 inch drive will cost about £25 - but you may decide to go for a larger drive.
http://www.amazon.co.uk/Generic-Hard-Disk-Drive-160GB/dp/B000OUI8OQ/ref=sr_1_fkmr0_2?s=computers&ie=UTF8&qid=1337534338&sr=1-2-fkmr0
