A few possible solutions, try them in order:
First try ONLY importing options / environments / fonts and colors.
If you have ReSharper, turn off color identifiers, which will ruin most color schemes. Go to ReSharper / Code Verification / Settings and turn off color identifiers.
Run RegEdit and export the backup first, and then delete the following keys: HKEY_CURRENT_USER \ Software \ Microsoft \ VisualStudio \ 10.0 \ FontAndColors \ Especially the cache and GUID. Then run VS and try to import again. It worked for me.
I have not even tried this, but as a last resort I will backup C: \ Users \ YOURUSERNAME \ Documents \ Visual Studio 2010 \ Settings \ CurrentSettings.vssettings and then edit this file by deleting the entire tag
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