Altera recommends that you disable any anti-virus scanner while downloading and installing the Altera® software using the Altera Software Installer version 10.0.
Some anti-virus scanners prevent the Altera Software Installer from properly downloading and installing the Altera software to your computer. In some cases, the installer program may indicate that the download and installation completed successfully, when in fact it did not.
Particular anti-virus scanners that may prevent a successful download and installation of the Altera software include AVG anti-virus software, ESET NOD32 anti-virus software, VirusBuster anti-virus software, and McAfee anti-virus software. However, Altera recommends that you disable any anti-virus scanner while downloading and installing using the Altera Software Installer version 10.0.
This problem is fixed in the Altera Software Installer version 10.0Rev2. You can download this version of the Altera Software Installer from the Download Center.