Fujitsu Amilo Pro V2055. Starts boot, performs RAM check, etc. then displays "cant find operating system". Checked that HDD is ok by reading it using another computer. Tried hard disk utility CD and get disk not found error. Is this a motherboard fault? How do I dismantle the laptop?

This usually means 1 of a few things..
1. Your Harddrive is bad
2. You got a boot sector virus, and your boot ini file is so badly infected, your computer can't find the boot file and you need to format your c:\ or d:\ drive....if you can get to your CMD window (command) but the way you bring it up is from CMD in start/run/CMD but since you can't even boot to your desktop...then you can choose a few options..

IF you have your your Windows Xp, or Windows Vista or Window 7 (depending on how you purchased your system, I'm thinking XP...since with Vista and Windows 7 you can reload to factory settings)

If you do have the disk....then you WILL have to reload your Operating System ....IF your harddrive isn't bad (have bad sectors or clusters) or is just "old" or was bumped severely and there's a dent on your harddrive preventing your boot ini file from being found...

There are so many things that could be wrong with it....Send me more infomation....
It's definitely NOT your motherboard...it's a harddrive issue...whether from a virus (which there are many out there that could infect or even rename your boot file....or your harddrive is BAD..
Either way...let me know and I can help you further!!!