Switched off during system restore - argh!

Hello,
I'm trying to sort out my Toshiba laptop and have followed some of the advice in this letter thread but I'm still stymied.

I was stupid enough to switch off my laptop during a system restore 'cos I was sure it had frozen. Now, I'm not so sure. Anyway, when I try to switch on I get the Windows XP loading screen but then it goes to a bluey screen with the message:

STOP: c0000135 {Unable To Locate Component} This application has failed to start because Secur32.dll was not found. Re-installing the application may fix this problem.

What the heck does that mean? From F8 I've tried the Reboot - nothing - and choosen the option Last Known Good Configuration (your most recent settings that worked) also, nothing. I've clicked on just about everything, to be honest. I'm not very computer literate so kinda thumped away at the options.

I do have a Product Recovery disc. So, big question, if I use it will I lose everything? Will I lose Windows XP - which came with the computer? I'm wary of using it in case there's nothing left on the laptop afterwards. What does it remove? I haven't installed much onto the Toshiba - just some security and pop up stopper. Luckily, I don't have anytning hugely important on it but I would hate to lose my vast photo collection as much of that is irreplaceable.

Is there anything I can do? I'm lost without it - feel as though I'm short a limb.Thanks.