error in installing SQL

Problem signature:
  Problem Event Name:   CLR20r3
  Problem Signature 01: setup100.exe
  Problem Signature 02: 10.0.2531.0
  Problem Signature 03: 49cfaf64
  Problem Signature 04: Microsoft.SqlServer.Chainer.Setup
  Problem Signature 05: 10.0.0.0
  Problem Signature 06: 49cfaf64
  Problem Signature 07: 4
  Problem Signature 08: a
  Problem Signature 09: System.IO.FileNotFoundException
  OS Version:   6.1.7601.2.1.0.256.1
  Locale ID:    1033
  Additional Information 1: 0a9e
  Additional Information 2: 0a9e372d3b4ad19135b953a78882e789
  Additional Information 3: 0a9e
  Additional Information 4: 0a9e372d3b4ad19135b953a78882e789

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