Sorry, I was too technical… let’s step-by-step.
-
You don’t have to worry that much with ‘decompression bombs’. It was an ‘old’ infection method.
-
You can manage the ‘infection’ sending the file to Chest (Quarantine) or deleting the file. But, take care, you must ‘need’ these files. Do you know what the strange file Install_Messenger_nous[1].exe do? Did you download it?
-
About avoiding to see these messages, well, you’ll need to edit the file avast4.ini file.
See here where it is located by default: http://forum.avast.com/index.php?topic=1647.msg10233#msg10233
Add (copy&paste) the following lines at the end of it (to disable the messages):
[Scanner]
MaxFileSizeToExtract_Scanner=0
MaxFileSizeToExtract_Resident=0
MaxFileSizeToExtract_Mail=0
MaxCompressionRatio_Scanner=0
MaxCompressionRatio_Resident=0
MaxCompressionRatio_Mail=0
CompressionCheckThreshold_Scanner=0
CompressionCheckThreshold_Resident=0
CompressionCheckThreshold_Mail=0