higina,
You should go ahead and upgrade to nLite 1.4.9.1. I don't think this will help, but it will eliminate one factor. Information in the error message all point to .NET Framework. Do you have all the latest updates? I remember when I updated .NET 2.0 some time ago, it was compiling routines for several boots after the update. Perhaps it is not through with that. If all else fails you might try the latest
.NET (MD5 D481CDA2625D9DD2731A00F482484D86) after removing your current one. Be sure to check the MD5 hashes for both nLite and .NET.
Hopefully someone will respond who has seen this error.
Good luck, John.