.NET Issues

Recently I had an issue with mscoreei.dll, specifically "C:\Windows\Microsoft.Net\Framework64\v4.030319\mscoreei.dll failed to load", a bit of searching pointed me at Microsoft's .NET Framework Repair Tool, which I got via Download Microsoft .NET Framework Repair Tool from Official Microsoft Download Center and found that it worked, so it is well worth a try. Another promising option, which I did not try was the System File Checker, so there is more information on that at Use the System File Checker tool to repair missing or corrupted system files.