AvastUI.exe-Application Error The instruction at 0x77e998dc9 referenced memory at 0x00000014

Hi Experts,
I updated my OS from Windows Vista 64-bit to Windows 7 64-bit. Everything was running well without any problem. However, I received an error message with Avast! Internet Security. It is showing an application error.
Have a look at the screenshot below. I uninstalled Avast and installed it again but no result. How can I get a remedy of this issue?
Please help.

AvastUI.exe-Application Error
The instruction at 0x77e98dc9 referenced memory at 0x00000014. The memory could not be written.
Click ok to terminate the program
