Re the first one... what is "this file"? Windows is trying to open a file, but doesn't know what program to use, so, correct me if I'm reading your description wrong:
- it sounds like this is happening when you log on, without you explicitly trying to open a file. If so, I think there's something in "Startup" that isn't working.
- from here, we obviously don't know what's in there, or whether it's good or bad. Click on Start / Programs / Startup. and have a look at what is listed there. Do you recognise everything in there? You might expect to see things from Microsoft, Adobe etc., maybe Symantec, but if unsure, see if you can find more info on Google or post the names for us to check.