According to Intuit, the error “This application failed to start because MSVCR80.DLL was not found” is an error that indicates your QuickBooks installation is damaged. The exact cause of the error hasn’t been determined.
Microsoft’s msvcr80.dll is a component of Visual C++ 2005 runtime environment that’s necessary for QuickBooks to function properly. If the file had been deleted, modified, or isn’t the correct version, QuickBooks will produce this error.
Fixing the error involves re-installing the msvcr80.dll file from the QuickBooks installation CD and repairing your QuickBooks installation.
To follow the troubleshooting steps to resolve this error, consult this Intuit knowledge base article.