Knights of the Old Republic 2 - Crashing!

I recently purchased Starwars: Knights of the Old Republic 2, it is brand new as I bought it from HMV. The CD's are flawless, not a single visible scratch.

So I start to play, and every now and again the game would crash. It would just completely freeze, so I would Ctrl + Alt + Del, select Task Manager and trying to end the Knights of the Old Republic 2 process wouldn't do anything, I would have to end the Dr Watson program error process to close the game.

This used to happen every half hour or hour, and I could bite my tongue and accept it, but now it is happening every minute.

I have tried to reinstall the game to a seperate directory but I still get the same problems.

I've changed my resolution, refresh rate, detail level, everything I can think of but nothing seems to do it.

Any help would be appreciated.

Also it might have something to do with this error, after inserting the game CD into the CD drive, selecting "Game" to start the game, I get a message:
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Star Wars: Knights of the Old Republic II: The Sith Lords: swkotor2.exe - No Disk

There is no disk in the drive. Please insert a disk into drive \Device\Harddisk1\DR3.

|Cancel| |Try Again| |Continue|
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If i hit Cancel or Continue the game just starts normally, but if I hit Try Again the error message just reappears.

I've e-mailed the Lucas Arts techincal support but haven't got a reply.

Any help on this would be great.

Thanks.

Daniel