|I'm totally with worldlibrary at reply #7 on this one. Switching to another AV in the middle of a problem does not seem to be a reasonable, and even less an effective solution.|
The OP did not bother mentioning whether there even WAS an AV program installed prior to this problem. Viruses may have been infecting this PC over a long time, corrupting system files, etc. The OP also did not make clear whether the problem occurred while installing AVG, or whether the installation was successful and a full scan was done, or what AVG may have found, and how that was handled.