Problems with Backup and Microsoft .NET framework version 2.0

Hi
I have no knowledge with computers. I have two issues, recently I got a Windows 7 for my birthday. I've been having some problems though. Everytime I log on a little screen comes up saying microsoft .NET framework version 2.0 is required to continue. I went to the microsoft website and downloaded a few things not knowing what to download but they all said .NEt framework version 2.0 but with more at the ending. Were do I go to download just the .NET framework version 2.0 that is also compatible with windows 7?

I am also having back up issues. i have an 8gb USB and my laptop backed up onto it once but when it tried to again it wouldn't let it. Usually a message in the action center said that I need to insert a blank cd or USB if it detected my USB it would start fine then a message popped up saying something along the lines of please label driver d (or something) and insert to continue...so I would have to cancel my back up.

I don't know if that makes any sense but if someone could help me that would be great because I have no idea on what to do.

Microsoft .NET framework version 3.5.1 is the default installation on Windows 7. I would guess that you have installed some software on your computer that needs an older version of Microsoft .NET Framework. Newer applications will need the newer version. Try safe mode to uninstall the application that is causing the problem.

You may need a blank usb drive to do the backup.

Edit:

If you are able to get into safe mode you can also use msconfig to see what what is starting on your computer at windows login.

Type msconfig in the search area of the start menu. Then select it from the menu that appears above.
Then click on the startup tab.