Computers! Can't Live With 'Em, Can't Live Without 'Em!

In the four months since I purchased my fancy new PC - with mum's money for my 40th birthday - I've had to call an engineer out twice and suffered a catastrophic system crash that required a four-hour total reboot/rebuild.

And then yesterday, I spent the whole afternoon in iTunes sorting out playlists to burn onto discs for incidental music for during our forthcoming wedding. Then as I was exiting my computer it told me it had some crucial updates to download and would do that during the shut down process.

I didn't give it a second thought ... until I went to start my computer again later on. And the following error message came up on the screen:

And now every time I turn on the machine that message comes up and I don't have a clue what it means! What are DLLs, how do they get moved (illegally or not), what do they do and more importantly what's happening in my computer since they're obviously not doing what they should be doing?

I've emailed my engineer again to ask him what I need to do and, in the meantime, although the machine still appears to be working okay I'm treating it with kid gloves and mentally calculating how I can justify buying a Mac!