Error on Episode 2 loading screen please help!

[Beansontoast]

I have purchased the Orange Box some months ago and have been content with advancing through Half Life 2 at my own pace. My computer isn't particulary powerful it is a slimline desktop model from "Stone Computers". Half Life 2 performed pretty well on medium graphics setting though i do get some fps issues in certain parts. I installed episode 1 via my steam games list and it runs if with quite bad fps issues. I installed episode 2 the same way as Half Life 2 and episode 1 , that went fine but when i loaded episode 2 up an error came up on the loading screen. This is the error exactly as it appears on my screen:
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Application error

The instruction at "0x108f806f" referenced memory at "0x01e8o410" The memory could not be read.
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It then tells me to "Click ok to terminate program" which results in my being taken straight back to my desktop. Can anyone please shed some light on this issue. Any assistance will be greatly appreciated.

[Weslay]

I've got a very similar problem, I've got HL2 and HL2:EP1 on my computer which run no problem, but when trying to load up EP2, it has the blurred picture of the citadel explosion with the 'Loading...' box bottom right. My cursor is still visible and movable but the game freezes and I can't quit, close, alt+ctrl+del or any such thing. I have to just reset my computer. It happens every time I try to run the game. I've tried reinstalling but apart from that I'm completely clueless! I don't even get an error msg like beansontoast.