Can’t figure out where the attachment disappeared to as it was apparent in the preview which I had a look at prior to sending.

Here is all the information requested:
Operating system: MS Windows 7 professional 64bit. SP1.
Current version of Avast is 8.0.1497

the following is a list of additional security software I have.
Windows Firewall and Defender are the only programs other than Avast that operates at start-up (“when the notification occurs”)
The following software is not included in start-up but actuated manually when required:
Spybot S&D
SuperAntiSpyware
AdwCleaner
Junkware removal tool.

The following is the content of the message received.
“The instruction at 0x77118e reference memory at 0x00000014. The memory could not be written.
Click on OK to terminate the program.”

Now to me this message clearly indicates that it originates from Microsoft but I am unable to find such error codes.